Tag: Electronic Vaporizer in UK

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful than cigarettes but may still be dangerous. Under which circumstances should a person use electronic cigarettes? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

Additionally, they're being marketed to children.

Do E-cigs Impact Society?

Are electronic cigarettes safe to use in public?

Many countries, states, cities, companies, bars and restaurants, and other organizations are banning the use of electronic cigarettes. There are a variety of reasons for their ban.

In 'Drugs And Society' by Glen R. Hanson, Peter J. Venturelli, Annette E. Fleckenstein, the implications the use of drugs has on society is explored in detail. The findings are quite fascinating.

De-icing your lungs?

Many articles about e-cigarettes will focus on the legality of their use and sale, their addictiveness, and the demographics who uses them. What few articles mention though, is what the ingredients in electronic cigarettes are and why you may not want them in your body.

Propylene glycol is basically plastic. Actually it's an additive for manufacturing plastic. The single largest use of PG is for the production of unsaturated polyester resins. It is also used as a humectant (an additive that keeps something moist), and as a preservative for food and tobacco. Mmm, yummy.

Propylene glycol has similar thermal properties to ethylene glycol in that it can lower the freezing point of water when added to it. As a result, propylene glycol is often used as aircraft de-icing fluid, according to Steve Ritter's article What's That Stuff?" on the C&EN website.

Another fun fact: disclosure of which chemicals are in any given electronic cigarette are often not made available by manufacturers or retailers. The most recent information regarding the health effects on humans of acute exposure to propylene glycol by inhalation is from 2002. Please find this information made available by the EPA at the bottom of this article.

Formaldehyde in Cigarettes; Nicotine could Kill a Child

You are probably not a doctor (although, you might be), and you probably rely on the advice of experts for medical information and health recommendations. Using your best judgement, do you think that electronic cigarettes are safe to use? Would you recommend using an electronic cigarette to your friends and family? How about your kids?

Take a look at this video from reports in France. It says that e-cigarettes contain level of formaldehyde near that of tobacco cigarettes. What? I do not know if that information is true, but if it is, it's not good!

The reports urge people to understand that electronic cigarettes are not healthy. Furthermore, the reports say that some models of e-cigarette do not have protective safety caps even though they have enough nicotine to kill a child. That is a liability. Yikes!

Quick facts

The molecular formula for propylene glycol is C3H8O2

It is a clear and colorless liquid and is non-corrosive

It is unknown whether or not is adversely affects human health

It is a main ingredient in electronic cigarettes and windshield washer liquid

Using it, you might look cool to some people (but they are pathetic losers)

Plastic boogers – your snot turns white and is now made of plastic

Ready for the formula? It's CH3CHOHCH2OH

The molecular formula for propylene glycol is C3H8O2. It is a clear and colourless liquid and is non-corrosive.

C3H8O2 can accumulate in your body from the use of shampoo, deodorant, moisturisers and creams, pain medication and a host of food products. So there's probably already enough in there without the use of e-cigs.

E-cigarettes offer you the opportunity to pay money to suck PG directly into the center of your body.

What Should You Do About It?

At best, e-cigarettes are neutral for your health and at worst they are detrimental to your health. How bad for you are they?

You'll need good luck if you are currently using an electronic cigarette! Because the health effects are largely unknown, using an e-cig is a gamble and you'll need all the luck you can get.

Enjoy!

Propylene Glycol Reference from the EPA

It looks like a few people have looked into it before. It's surprising there's not a lot of available data as to the effects of inhalation on humans. Shocking!

Burkhart, J., Piacitelli, C., Schwegler-Berry, D., and Jones, W. Environmental study of nylon flocking process. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH PART A; 57 (1).1999.1-23.AB - BIOSIS COPYRIGHT: BIOL ABS.Environmental measurements for a variety of gas, particulate, and microbiological agents have been made in order to characterize exposures associated with the nylon flocking process.Of all agents measured, particulate is the predominant exposure.Levels of total particulate ranged from 0.1 to 240 mg/m3 ( x = 11.4 mg/m3).Average respirable particulate was 2.2 mg/m3, ranging from 0.5 to 39.9 mg/m3.Highest levels of particulates were found in the flocking room, and direct reading dust measuremen veral of which were linked directly to the process.Of special interest were elongated respirable particles, which by microscopic analysis, complemented with melting-point determination, were found to be shreds of nylon. 1999. Code: 8

Corley, R. A., Crissman, J. W., Redmond, J. M., McGuirk, R. J., Cieszlak, F. S., and Stott, W. T. Adaptive Metabolic and Pathologic Changes following Chronic Inhalation of Propylene Glycol Monomethyl Ether in Rats and Mice. Occupational Hygiene, Vol.2, Nos.1-6, pages 319-328, 24 references, 1996 AB - The temporal relationships between propylene-glycol-monomethyl-ether (107982) (PGME) induced metabolic and morphological changes in rats and mice which have been chronically exposed to up to 3,000 parts per million (ppm) of PGME vapors were characterized.B6C3F1-mice and F344-rats were exposed to 300, 1,000, or 3,000ppm for 6 hours a day, 5 days a week, for up to 2 years.Results indicated that there is potential for adaptive biochemical and cellular changes in response to chemical exposure to modify the toxicity of PGME in rats and mice.Nearly all inhaled PGME was absorbed, resulting in high systemic levels of PGME.These levels may result in central nervous system depression and the clinically observable sedation of exposed animals.A disruption in male rats was noted in the processing of alpha2micro-globulin resulting in mild degenerative effects in renal tubule epithelial cells.The pronounced sedation of rats and mice exposed to 3,000ppm resolved by the second week of exposure.The induction of O-dealkylase activity in these animals suggests an increase in the potential of metabolized PGME via its major metabolic route to propylene-glycol and then to carbon-dioxide.Exposed animals may also have effectively enhanced PGME metabolism by increasing the number of hepatocytes in response to PGME exposure resulting in the increase in liver weights.Clearly defined, treatment related renal effects were only observed in male rats.The authors conclude that high concentrations of PGME cause an adaptive hepatic response in both sexes of rats and mice that is partially reversed in rats. 1996. Code: 8

Ishiwata, H., Nishijima, M., Fukasawa, Y., Ito, Y., and Yamada, T. Evaluation of the contents of BHA, BHT, propylene glycol, and sodium saccharin in foods and estimation of daily intake based on the results of official inspection in Japan in fiscal year 1994. Journal of the Food Hygienic Society of Japan; 39 (2).1998.89-100. 1998. Code: 8

Kucherenko, Y. U. and Moiseev, V. A. The use of 1H-NMR spectroscopy and refractometry for investigation of the distribution of nonelectrolytes of N-alcohol series between human red blood cells and extracellular medium. Membr Cell Biol 13(5):633-44. 2000. Code: 8

An electronic cigarette is a battery-powered vaporizer.[1] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[3] When the user pushes a button,[4] or (in some variations) activates a pressure sensor by inhaling, the heating element then atomizes the liquid solution[5] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[7] The aerosol provides a flavor and feel similar to tobacco smoking.[1]

There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] Most cigalikes look like cigarettes but there is some variation in size.[11] Second generation devices are larger overall and look less like tobacco cigarettes.[12] Third generation devices include mechanical mods and variable voltage devices.[10] The fourth generation includes Sub ohm tanks and temperature control devices.[13] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[15]

A later-generation box mod e-cigarette. Image courtesy of Ecigclick

An e-cigarette is a handheld battery-powered vaporizer that simulates smoking, but without tobacco combustion.[1] Once the user inhales, the airflow activates the pressure sensor, and then the heating element atomizes the liquid solution.[5] Most devices have a manual push-button switch to turn them on or off.[16] E-cigarettes do not turn on by trying to "light" the device with a flame.[4] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] However, variable voltage devices can raise the temperature.[17] A glycerin-only liquid vaporizes at a higher temperature than a propylene glycol-glycerin liquid.[17] Rather than cigarette smoke, the user inhales an aerosol, commonly but inaccurately called vapor.[7] E-cigarettes do not create vapor between puffs.[18]

Vaping is different than tobacco smoking, but there are some similarities with their behavioral habits, including the hand-to-mouth action and a vapor that looks like cigarette smoke.[1] E-cigarettes provide a flavor and feel similar to smoking.[1] A noticeable difference between the traditional cigarette and the e-cigarette is sense of touch.[1] A traditional cigarette is smooth and light but an e-cigarette is rigid, cold and slightly heavier.[1] Since e-cigarettes are more complex than traditional cigarettes, a learning curve is needed to use them correctly.[19]

Compared to traditional cigarettes, the general e-cigarette puff time is much longer, and requires a more forceful suction than a regular cigarette.[20] The volume of vapor created by e-cigarette devices in 2012 declined with vaping.[1] Thus, to create the same volume of vapor increasing puff force is needed.[1] Later-generation e-cigarettes with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[21] Many e-cigarette versions include a voltage potentiometer to adjust the volume of vapor created.[4] The amount of vapor produced is controlled by the power from the battery, which has led some users to adjust their devices to increase battery power.[6]

An ordinary cigarette compared to a "cigalike" e-cigarette

E-cigarettes are usually approximately cylindrical, with many variations: pen-styles, tank-styles etc.[22] Some e-cigarettes look like traditional cigarettes, but others do not.[19] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8]

The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] The only exception to this are mechanical e-cigarettes (mods) which contain no electronics and the circuit is closed by using a mechanical action switch.[23] E-cigarettes are sold in disposable or reusable variants.[8] Disposable e-cigarettes are discarded once the liquid in the cartridge is used up, while rechargeable e-cigarettes may be used indefinitely.[24] A disposable e-cigarette lasts to around 400 puffs.[25] Reusable e-cigarettes are refilled by hand or exchanged for pre-filled cartridges, and general cleaning is required.[4] A wide range of disposable and reusable e-cigarettes exist.[26] Disposable e-cigarettes are offered for a few dollars, and higher-priced reusable e-cigarettes involve an up-front investment for a starter kit.[19] Some e-cigarettes have a LED at the tip to resemble the glow of burning tobacco.[21] The LED may also indicate the battery status.[1] The LED is not generally used in personal vaporizers or mods.[2]

First-generation e-cigarettes usually simulated smoking implements, such as cigarettes or cigars, in their use and appearance.[10] Later-generation e-cigarettes often called mods, PVs (personal vaporizer) or APVs (advanced personal vaporizer) have an increased nicotine-dispersal performance,[10] house higher capacity batteries, and come in various shapes such as metal tubes and boxes.[27] They contain silver, steel, metals, ceramics, plastics, fibers, aluminum, rubber and spume, and lithium batteries.[28] A growing subclass of vapers called cloud-chasers configure their atomizers to produce large amounts of vapor by using low-resistance heating coils.[29] This practice is known as cloud-chasing.[30] Many e-cigarettes are made of standardized replaceable parts that are interchangeable between brands.[31] A wide array of component combinations exists.[32] Many e-cigarettes are sold with a USB charger.[33] E-cigarettes that resemble pens or USB memory sticks are also sold for those who may want to use the device unobtrusively.[34]

As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9]

Various types of e-cigarettes.

First-generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] The three parts of a cigalike e-cigarette initially were a cartridge, an atomizer, and a battery.[35] A cigalike e-cigarette currently contains a cartomizer (cartridge atomizer), which is connected to a battery.[35] Most cigalikes look like cigarettes but there is some variation in size.[35]

They may be a single unit comprising a battery, coil and filling saturated with e-juice in a single tube to be used and discarded after the battery or e-liquid is depleted.[10] They may also be a reusable device with a battery and cartridge called a cartomizer.[12] The cartomizer cartridge can be separated from the battery so the battery can be charged and the empty cartomizer replaced when the e-juice runs out.[10]

The battery section may contain an electronic airflow sensor triggered by drawing breath through the device.[12] Other models use a power button that must be held during operation.[12] An LED in the power button or on the end of the device may also show when the device is vaporizing.[36]

Charging is commonly accomplished with a USB charger that attaches to the battery.[37] Some manufacturers also have a cigarette pack-shaped portable charging case (PCC), which contains a larger battery capable of recharging the individual e-cigarette batteries.[38] Reusable devices can come in a kit that contains a battery, a charger, and at least one cartridge.[38] Varying nicotine concentrations are available and nicotine delivery to the user also varies based on different cartomizers, e-juice mixtures, and power supplied by the battery.[22]

These manufacturing differences affect the way e-cigarettes convert the liquid solution to an aerosol, and thus the levels of ingredients, that are delivered to the user and the surrounding air for any given liquid.[22] First-generation e-cigarettes use lower voltages, around 3.7 V.[39]

Second-generation PV.

Second generation devices tend to be used by people with more experience.[12] They are larger overall and look less like tobacco cigarettes.[12] They usually consist of two sections, basically a tank and a separate battery. Their batteries have higher capacity, and are not removable.[10] Being rechargeable, they use a USB charger that attaches to the battery with a threaded connector. Some batteries have a "passthrough" feature so they can be used even while they are charging.[40][41]

Second-generation e-cigarettes commonly use a tank or a "clearomizer".[12] Clearomizer tanks are meant to be refilled with e-juice, while cartomizers are not.[10] Because they're refillable and the battery is rechargeable, their cost of operation is lower.[10] Hovever, they can also use cartomizers, which are pre-filled only.[10]

Some cheaper battery sections use a microphone that detects the turbulence of the air passing through to activate the device when the user inhales.[42] Other batteries like the eGo style can use an integrated circuit, as well as a button for manual activation. The LED shows battery status.[42] The power button can also switch off the battery so it is not activated accidentally.[43] Second generation e-cigarettes may have lower voltages, around 3.7 V.[39] However, adjustable-voltage devices can be set between 3 V and 6 V.[44]

Third-generation PV.

The third-generation includes mechanical mods and variable voltage devices.[45][46] Battery sections are commonly called "mods," referencing their past when user modification was common.[10] Mechanical mods do not contain integrated circuits.[46] They are commonly cylindrical or box-shaped, and typical housing materials are wood, aluminium, stainless steel, or brass.[47] A larger "box mod" can hold bigger and sometimes multiple batteries.[47]

Mechanical mods and variable devices use larger batteries than those found in previous generations.[48] Common battery sizes used are 18350, 18490, 18500 and 18650.[49] The battery is often removable,[46] so it can be changed when depleted. The battery must be removed and charged externally.[46]

Variable devices permit setting wattage, voltage, or both.[40][46] These often have a USB connector for recharging; some can be used while charging, called a "passthrough" feature.[40][50] Mechanical mods do not contain integrated circuits.[46]

The power section may include additional options such as screen readout, support for a wide range of internal batteries, and compatibility with different types of atomizers.[12] Third-generation devices can have rebuildable atomizers with different wicking materials.[10][12] These rebuildables use handmade coils that can be installed in the atomizer to increase vapor production.[48] Hardware in this generation is sometimes modified to increase power or flavor.[51]

The larger battery sections used also allow larger tanks to be attached that can hold more e-liquid.[47] Recent devices can go up to 8 V, which can heat the e-liquid significantly more than earlier generations.[39]

A fourth-generation e-cigarette became available in the U.S. in 2014.[21] Fourth-generation e-cigarettes can be made from stainless steel and pyrex glass, and contain very little plastics.[13] Included in the fourth-generation are Sub ohm tanks and temperature control devices.[13]

An e-cigarette atomizer with the coil (heating element) in view.

An atomizer comprises a small heating element that vaporizes e-liquid and a wicking material that draws liquid onto the coil.[3] Along with a battery and e-liquid the atomizer is the main component of every personal vaporizer.[12] A small length of resistance wire is coiled around the wicking material and connected to the integrated circuit, or in the case of mechanical devices, the atomizer is connected directly to the battery through either a 510, 808, or ego threaded connector.[52] 510 being the most common.[52] When activated, the resistance wire coil heats up and vaporizes the liquid, which is then inhaled by the user.[53]

The electrical resistance of the coil, the voltage output of the device, the airflow of the atomizer and the efficiency of the wick all affect the vapor coming from the atomizer.[54] They also affect the vapor quantity or volume yielded.[54]

Atomizer coils made of kanthal usually have resistances that vary from 0.4Ω (ohms) to 2.8Ω.[54] Coils of lower ohms have increased vapor production but could risk fire and dangerous battery failures if the user is not knowledgeable enough about electrical principles and how they relate to battery safety.[55]

The cartomizer was invented in 2007, integrating the heating coil into the liquid chamber.[57] A "cartomizer" (a portmanteau of cartridge and atomizer.[58]) or "carto" consists of an atomizer surrounded by a liquid-soaked poly-foam that acts as an e-liquid holder.[3] They can have up to 3 coils and each coil will increase vapor production.[3] The cartomizer is usually discarded when the e-liquid starts to taste burnt, which usually happens when the e-cigarette is activated with a dry coil or when the cartomizer gets consistently flooded (gurgling) because of sedimentation of the wick.[3] Most cartomizers are refillable even if not advertised as such.[3][59]

Cartomizers can be used on their own or in conjunction with a tank that allows more e-liquid capacity.[3] The portmanteau word "cartotank" has been coined for this.[60] When used in a tank, the cartomizer is inserted in a plastic, glass or metal tube and holes or slots have to be punched on the sides of the cartomizer so liquid can reach the coil.[3]

eGo style e-cigarette with a top-coil clearomizer. Silica fibers are hanging down freely inside of the tank, drawing e-liquid by capillary action to the coil that is located directly under the mouthpiece.

The clearomizer was invented in 2009 that originated from the cartomizer design.[57] It contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component.[57] This allows the user to monitor the liquid level in the device.[57] Clearomizers or "clearos", are like cartotanks, in that an atomizer is inserted into the tank.[61] There are different wicking systems used inside clearomizers.[3] Some rely on gravity to bring the e-liquid to the wick and coil assembly (bottom coil clearomizers for example) and others rely on capillary action or to some degree the user agitating the e-liquid while handling the clearomizer (top coil clearomizers).[3][62] The coil and wicks are typically inside a prefabricated assembly or "head" that is replaceable by the user.[63]

Clearomizers are made with adjustable air flow control.[64] Tanks can be plastic or borosilicate glass.[65] Some flavors of e-juice have been known to damage plastic clearomizer tanks.[65]

Box mod e-cigarette fitted with a rebuildable dripping atomizer (RDA). A view of the RDA deck showing the wicks and coils, juice is dripped into a hopper where the wicks rest as well as atop the coil assembly.

A rebuildable atomizer or an RBA is an atomizer that allows the user to assemble or "build" the wick and coil themselves instead of replacing them with off-the-shelf atomizer "heads".[10] They are generally considered advanced devices.[66] They also allow the user to build atomizers at any desired electrical resistance.[10]

These atomizers are divided into two main categories; rebuildable tank atomizers (RTAs) and rebuildable dripping atomizers (RDAs).[67]

Rebuildable tank atomizers (RTAs) have a tank to hold liquid that is absorbed by the wick.[68] They can hold up to 4ml of e-liquid.[69] The tank can be either plastic, glass, or metal.[65] One form of tank atomizers was the Genesis style atomizers.[68] They can use ceramic wicks, stainless steel mesh or rope for wicking material.[68] The steel wick must be oxidized to prevent arcing of the coil.[68] Another type is the Sub ohm tank.[69] These tanks have rebuildabe or RBA kits.[69] They can also use coilheads of 0.2ohm 0.4hom and 0.5ohm.[69] These coilheads can have stainless steel coils.[70]

Rebuildable dripping atomizers (RDAs) are atomizers where the e-juice is dripped directly onto the coil and wick.[71] The common nicotine strength of e-liquids used in RDA's is 3 mg and 6 mg.[71] Liquids used in RDA's tend to have more vegetable glycerin.[71] They typically consist only of an atomizer "building deck", commonly with three posts with holes drilled in them, which can accept one or more coils.[51] The user needs to manually keep the atomizer wet by dripping liquid on the bare wick and coil assembly, hence their name.[71]

Kanthal wire is commonly used in both RDA's and RTA's.[71] They can also use nickel wire or titanium wire for temperature control.[71]

Variable devices are variable wattage, variable voltage or both.[40][46] Variable power and/or variable voltage have a electronic chip allowing the user to adjust the power applied to the heating element.[12][46] The amount of power applied to the coil affects the heat produced, thus changing the vapor output.[12][32] Greater heat from the coil increases vapor production.[32] Variable power devices monitor the coil's resistance and automatically adjust the voltage to apply the user-specified level of power to the coil.[72] Recent devices can go up to 8 V.[39]

They are often rectangular but can also be cylindrical.[47] They usually have a screen to show information such as voltage, power, and resistance of the coil.[73] To adjust the settings, the user presses buttons or rotates a dial to turn the power up or down.[32] Some of these devices include additional settings through their menu system such as: atomizer resistance meter, remaining battery voltage, puff counter, and power-off or lock.[74] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[4] Smaller devices contain smaller batteries and are easier to carry but typically require more repeated recharging.[4] Some e-cigarettes use a long lasting rechargeable battery, a non-rechargeable battery or a replaceable battery that is either rechargeable or non-rechargeable for power.[26] Some companies offer portable chargeable cases to recharge e-cigarettes.[26] Nickel-cadmium (NiCad), nickel metal-hydride (NiMh), lithium ion (Li-ion), alkaline and lithium polymer (Li-poly), and lithium manganese (LiMn) batteries have been used for the e-cigarettes power source.[26]

PV with variable and regulated power offering battery protection.

Temperature control devices allow the user to set the temperature.[71] There is a predictable change to the resistance of a coil when it is heated.[75] The resistance changes are different for different types of wires, and must have a high temperature coefficient of resistance.[75] Temperature control is done by detecting that resistance change to estimate the temperature and adjusting the voltage to the coil to match that estimate.[76]

Nickel, titanium, NiFe alloys, and certain grades of stainless steel are common materials used for wire in temperature control.[71] The most common wire used, kanthal, cannot be used because it has a stable resistance regardless of the coil temperature.[75] Nickel was the first wire used because of it has the highest coefficient of the common metals.[75]

Mechanical PV with a rebuildable atomizer.

The temperature can be adjusted in Celsius or Fahrenheit.[77] The DNA40 and SX350J are common control boards used in temperature control devices.[78] Temperature control can stop dry wicks from burning, or e-liquid overheating.[78]

Mechanical PVs or mechanical "mods", often called "mechs", are devices without integrated circuits, electronic battery protection, or voltage regulation.[46] They are activated by a switch.[71] They rely on the natural voltage output of the battery and the metal that the mod is made of often is used as part of the circuit itself.[79]

The term "mod" was originally used instead of "modification".[10] Users would modify existing hardware to get better performance, and as an alternative to the e-cigarettes that looked like traditional cigarettes.[32] Users would also modify other unrelated items like flashlights as battery compartments to power atomizers.[32][47] The word mod is often used to describe most personal vaporizers.[3]

Mechanical PVs have no power regulation and are unprotected.[71] Because of this ensuring that the battery does not over-discharge and that the resistance of the atomizer requires amperage within the safety limits of the battery is the responsibility of the user.[79]

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

(Redirected from E-liquid) Aerosol (vapor) exhaled by an e-cigarette user.

The aerosol of electronic cigarettes is generated when the e-liquid reaches a temperature of roughly 100–250 °C within a chamber.[1] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[2] The aerosol provides a flavor and feel similar to tobacco smoking.[3] In physics, a vapor is a substance in the gas phase whereas an aerosol is a suspension of tiny particles of liquid, solid or both within a gas.[2] Vapor from an electronic cigarette simulates tobacco smoke, but the process of burning tobacco does not occur.[3] The aerosol is made-up of liquid sub-micron particles of condensed vapor,[4] which mostly consist of propylene glycol, glycerol, water, flavorings, nicotine, and other chemicals.[5] The various chemicals in the aerosol give rise to many issues concerning the safety of electronic cigarettes that have been much discussed.[2][5][6] After a puff, inhalation of the aerosol travels from the device into the mouth and lungs.[2] A 2014 review found that the particles emitted by e-cigarettes are comparable in size and number to particles in cigarette smoke, with the majority of them in the ultrafine range. The particles are of the ultrafine size which can go deep in the lungs and then into the systemic circulation. A 2014 review said local pulmonary toxicity may occur because metal nanoparticles can deposit in the lungs.[6] Others show that the quantities of metals emitted are minimal and permissible by medicinal standards.[5][7][8]

Various bottles of e-liquid.

After the aerosol is inhaled, it is exhaled.[2] Emissions from electronic cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different.[5] The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled vapor.[9] Bystanders are exposed to these particles from exhaled e-cigarette vapor.[6] There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors, and have significant adverse effects.[10][11][12] Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted.[13] Thus, cardiocirculatory effects caused by carbon monoxide are not likely.[13] E-cigarette use by an expectant parent might lead to inadvertent health risks to offspring.[14] E-cigarettes pose many safety concerns to children.[14] For example, indoor surfaces can accumulate nicotine where e-cigarettes were used, which may be inhaled by children, particularly youngsters, long after they were used.[14]

E-liquid is the mixture used in vapor products such as electronic cigarettes.[15] The main ingredients in the e-liquid usually are propylene glycol, glycerin, nicotine, and flavorings.[16] However, there are e-liquids sold without propylene glycol, nicotine, or flavors.[15][17][18] The liquid typically contains 95% propylene glycol and glycerin.[19] Propylene glycol and glycerine are used to produce the vapor while the flavoring provides the taste and aroma.[20] The flavorings may be natural or artificial.[9] About 8,000 flavors exist as of 2014.[21] There are many e-liquids manufacturers in the USA and worldwide.[22] While there are currently no US Food and Drug Administration (FDA) manufacturing standards for e-liquid, the FDA has proposed regulations that were expected to be finalized in late 2015.[23] Industry standards have been created and published by the American E-liquid Manufacturing Standards Association (AEMSA).[24]

The vapor can contain nicotine and usually contains vegetable glycerin, propylene glycol, flavors and aroma transporters.[8] The nicotine levels in the vapor varies either from puff-to-puff or among products of the same company.[2] A 2015 report commissioned by Public Health England concluded that e-cigarettes "release negligible levels of nicotine into ambient air".[25] E-cigarettes without nicotine are also available.[26] The vapor may also contain tiny amounts of toxicants, carcinogens, and heavy metals.[6][8] Contamination with various chemicals has been identified.[9] E-cigarette makers do not fully disclose information on the chemicals that can be released or synthesized during use.[2] The metals have been found in trace amounts in the vapor, some of them at higher amounts than in cigarette smoke.[5] The peak concentration of nicotine delivered by e-cigarette use is comparable to that produced by conventional cigarette smoking.[27]

An example of a commercial e-liquid and an advanced personal vaporizer.

E-liquid,[28] e-fluid, or e-juice[29] is the mixture used in vapor products including e-cigarettes.[15] E-Liquids come in many variations, including different nicotine strengths and many different flavors.[30] The main ingredients are propylene glycol, glycerine, and flavorings; and most often, nicotine in liquid form.[16] The liquid typically contains 95% propylene glycol and glycerin, and the remaining 5% being flavorings and nicotine.[19] E-liquid can be made with or without nicotine, with >90% of e-liquids containing some level of nicotine.[31] The most regularly used base carrier chemical is propylene glycol with or without glycerin.[6] E-liquid containing glycerin and water made without propylene glycol are also sold.[15] Unless clearly stated, it is uncertain whether the nicotine used in e-liquid is manufactured using a United States Pharmacopeia (USP) grade nicotine, a tobacco plant extract, tobacco dust or a synthetic nicotine.[32] Most e-cigarette liquids contain nicotine, but the level of nicotine varies depending on user-preference and manufacturers.[26] Although some e-juice is nicotine-free, surveys demonstrate that 97% of responders use products that contain nicotine.[17] A 2015 review suggests that 1% of users use liquid without nicotine.[33]

The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[34] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[35] When the user pushes a button.[36] or inhales a pressure sensor activates the heating element that atomizes the liquid solution;[37] The e-liquid reaches a temperature of roughly 100–250 °C within a chamber to create an aerosolized vapor.[1] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[2] The aerosol provides a flavor and feel similar to tobacco smoking.[3] However, variable voltage devices can raise the temperature where the user adjusts the vapor.[9] The vapor contains similar chemicals to the e-liquid which vary in composition and concentration across and within manufacturers.[2]

E-cigarettes produce particles, in the form of an aerosol.[2][38] In physics, a vapor is a substance in the gas phase whereas an aerosol is a suspension of tiny particles of liquid, solid or both within a gas.[2] The aerosol is made-up of liquid sub-micron particles of condensed vapor,[38] which mostly consist of propylene glycol, glycerol, water, flavorings, nicotine, and other chemicals.[5] This aerosol that is produces resembles cigarette smoke.[2] After a puff, inhalation of the aerosol travels from the device into the mouth and lungs.[2]

A 2014 review found that the particles emitted by e-cigarettes are comparable in size and number to particles in cigarette smoke, with the majority of them in the ultrafine range. The ultrafine particles can go deep in the lungs and then into the systemic circulation. Pulmonary toxicity may occur because metal nanoparticles can deposit in the lungs.[6] The review also found that fine particles can be chemically intricate and not uniform, and what a particle is made of, the exact harmful elements, and the importance of the size of the particle is mostly unknown. They found that because these things are uncertain, it is not clear whether the ultrafine particles in e-cigarette vapor have health effects similar to those produced by traditional cigarettes.[6]

A 2014 WHO report found e-cigarettes release a lower level of particles than traditional cigarettes.[39] Comparable to a traditional cigarette, e-cigarette particles are tiny enough to enter the alveoli, enabling nicotine absorption.[29] E-cigarettes companies assert that the particulates produced by an e-cigarette are too tiny to be deposited in the alveoli.[40] Exactly what comprises the vapor varies in composition and concentration across and within manufacturers.[2] Different devices generate different particle sizes and cause different depositions in the respiratory tract, even from the same nicotine liquid.[41] Reports in the literature have shown respiratory and cardiovascular effects by these smaller size particles, suggesting a possible health concern.[42]

After the aerosol is inhaled, it is exhaled.[2] Emissions from electronic cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different.[5] The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled vapor.[9] The exhaled aerosol particle concentration is 5 times lower from an e-cigarette than from a combustible tobacco cigarette.[43] The density of particles in the vapor is lower than in cigarette smoke by a factor of between 6 and 880 times lower.[5]

For particulate matter emissions, e-cigarettes slightly exceeded the WHO guidelines, but emissions were 15 times less than traditional cigarette use.[44] In January 2014, the International Union Against Tuberculosis and Lung Disease stated "Adverse health effects for exposed third parties (second-hand exposure) cannot be excluded because the use of electronic cigarettes leads to emission of fine and ultrafine inhalable liquid particles, nicotine and cancer-causing substances into indoor air."[45] The dense vapor consists of liquid sub-micron droplets.[38][dead link]

Since e-cigarettes have not been widely used long enough for evaluation, the long-term health effects from the second-hand vapor are not known.[6] There is insufficient data to determine the impact on public health from e-cigarettes.[46] The potential harm to bystanders from e-cigarettes is unknown.[47] This is because no long-term data is available.[8]

Since e-cigarettes do not burn (or contain) tobacco, no side-stream smoke or any cigarette smoke is produced.[6] Only what is exhaled by e-cigarettes users enters the surrounding air.[8] Exhaled vapor consists of nicotine and some other particles, primarily consisting of flavors, aroma transporters, glycerin and propylene glycol.[8] Bystanders are exposed to these particles from exhaled e-cigarette vapor.[6] A mixture of harmful substances, particularly nicotine, ultrafine particles, and volatile organic compounds can be exhaled into the air.[48] The liquid particles condenses into a viewable fog.[9] The vapor is in the air for a short time, with a half-life of about 10 seconds; traditional cigarette smoke is in the air 100 times longer.[9] This is because of fast revaporization at room temperature.[9]

There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors, and have significant adverse effects.[10][12] Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted.[13] Thus, cardiocirculatory effects caused by carbon monoxide are not likely.[13] However, in an experimental study, e-cigarettes increased levels of carcinogenic polycyclic aromatic hydrocarbons in the surrounding air.[13]

E-cigarettes used in indoor environments can put at risk nonsmokers to elevated levels of nicotine and aerosol emissions.[43] Nonsmokers exposed to e-cigarette aerosol produced by a machine and pumped into a room were found to have detectable levels of the nicotine metabolite cotinine in their blood. The same study stated that 80% of nicotine is normally absorbed by the user, so these results may be higher than in actual second hand exposure.[6] In 2015 a report commissioned by Public Health England concluded that e-cigarettes "release negligible levels of nicotine into ambient air with no identified health risks to bystanders".[25]

A 2014 review of limited data concluded this vapor can cause indoor air pollution and is not just water vapor as is frequently stated in the advertising of e-cigarettes.[6] A 2014 practice guideline by NPS MedicineWise states, "Although data on health effects of passive vapour are currently lacking, the risks are argued to be small, but claims that e-cigarettes emit only water vapour are nevertheless incorrect. Serum cotinine levels (a metabolite of nicotine) have been found to be similar in bystanders exposed to either e-cigarette vapour or cigarette smoke."[49][50] The 2015 California Department of Public Health has reported that "Mainstream and second hand e-cigarette aerosol has been found to contain at least ten chemicals that are on California's Proposition 65 list of chemicals known to cause cancer, birth defects, or other reproductive harm."[51] However, it has been demonstrated that e-cigarettes causes nonusers to be exposed to nicotine but not to tobacco-related combustion toxicants.[10]

A no smoking or vaping sign from the US.

A white paper published in 2014 by the American Industrial Hygiene Association concluded e-cigarettes emit airborne contaminants that may be inhaled by the user and those nearby.[42] They urged indoors restrictions similar to smoking bans, until research has shown the aerosol has no risk of harm.[42] A 2014 review indicated that the levels of inhaled contaminants from the e-cigarette vapor are not of significant health concern for human exposures by the standards used in workplaces to ensure safety.[26] The use of e-cigarettes in a smoke-free area could expose non-users to toxins.[52] The effect on bystanders would likely be much less harmful than traditional cigarettes.[8]

2014 WHO report stated passive exposure was as a concern, indicating that current evidence is insufficient to determine whether the levels of exhaled vapor are safe to involuntarily exposed bystanders.[39] The report stated that "it is unknown if the increased exposure to toxicants and particles in exhaled aerosol will lead to an increased risk of disease and death among bystanders."[39] The British Medical Association (BMA) reported in 2013 that there are "concerns that the use of e-cigarettes could threaten the norm of not smoking in public places and workplaces."[53]

As of 2013[update], the only clinical study currently published evaluating the respiratory effects of passive vaping found no adverse effects were detected.[5] A 2014 review found it is safe to infer that their effects on bystanders are minimal in comparison to traditional cigarettes.[5] A E-cigarette vapor has notably fewer toxicants than cigarette smoke and is likely to pose less harm to users or bystanders.[6]

E-cigarette use by a parent might lead to inadvertent health risks to offspring.[14] E-cigarettes pose many safety concerns to children.[14] For example, indoor surfaces can accumulate nicotine where e-cigarettes were used, which may be inhaled by children, particularly youngsters, long after they were used.[14] A policy statement by the American Association for Cancer Research and the American Society of Clinical Oncology has reported that "Third-hand exposure occurs when nicotine and other chemicals from second-hand aerosol deposit on surfaces, exposing people through touch, ingestion, and inhalation".[17] Public health England, looking at the available research said the amount of nicotine deposited was low and that an infant would have to lick 30 square meters to be exposed to 1 mg of nicotine.[25] The statement noted there are no published studies of third hand exposure from e-cigarettes, however initial data suggests that nicotine from e-cigarettes may stick to surfaces and would be hard to remove.[17]

The e-liquid is sold in bottles or pre-filled disposable cartridges, or as a kit for consumers to make their own e-juices.[54] Some vendors of e-liquids, offer options to change the amounts of flavorings or nicotine strengths, and build each bottle customized for the purchaser.[54] E-liquids are made with various tobacco, fruit, and other flavors,[6] as well as variable nicotine concentrations (including nicotine-free versions).[16] The standard notation "mg/ml" is often used on labels to denote nicotine concentration, and is sometimes shortened to "mg".[55] In surveys of regular e-cigarette users, the most popular e-liquids have a nicotine content of 18 mg/ml, and the preferred flavors were largely tobacco, mint and fruit.[8] A cartridge may contain 0 to 20 mg of nicotine.[48] EU regulations cap the concentration of nicotine in e-liquid at a maximum of 20 mg/mL.[29] A refill bottle can contain up to 1 g of nicotine.[48] Refill liquids are often sold in the size range from 15 to 30 mL.[56] One cartridge may typically last as long as one pack of cigarettes.[57] Some liquids without flavoring is also sold.[18] The flavorings may be natural or artificial.[9] There is even certified organic liquid.[58] About 8,000 flavors exist as of 2014.[21] A user does not normally consume a whole cartridge in a single session.[59] Most e-liquids are produced by a few manufacturers in China, the US and Europe.[8] An e-cigarette user will usually obtain 300 to 500 puffs per mL of liquid.[56]

The two most common e-liquid bases are propylene glycol (PG) and vegetable glycerin (VG).[60] Propylene glycol is tasteless and odorless, and therefore it doesn't affect the flavor of the e-liquid. It is known, however, to cause allergic reactions in some users, and in such case it is advised to stop the use immediately. Vegetable glycerin, on the other hand, is a lot thicker in consistency, and it doesn't cause allergic reactions. It also produces significantly more vapor, which has a slight sweet taste.[61][unreliable source?]

E-liquids are manufactured by many producers, both in the US and across the world.[22] First tier manufacturers use lab suits, gloves, hair covers, inside of certified clean rooms with air filtration similar to pharmaceutical-grade production areas.[22]

Standards for e-liquid manufacturing have been created by American E-liquid Manufacturing Standards Association (AEMSA), which is trade association dedicated to creating responsible and sustainable standards for the safe manufacturing of e-liquids used in vapor products.[62] AEMSA has published a comprehensive list standards and best known methods, which are openly available for use by any manufacturer of e-Liquids. The AEMSA standards cover nicotine, ingredients, sanitary manufacturing rooms, safety packaging, age restrictions, and labeling.[24]

There are no current governmental or US Food and Drug Administration (FDA) manufacturing standards for e-liquid. The FDA has sought to regulate e-liquid through use of the Tobacco Control Act, passed into law in 2009. In April 2014, the FDA issued its "Deeming" proposals for public comment, which would cover e-liquids manufacturing. The Final Rule, (in final form) giving the FDA authority to regulate e-liquids was released on May 5th 2016.[63]

Electronic cigarette aerosol and e-liquid

UK

The entering into force of the requirements of the European tobacco products directive in Estonia made e-cigarette seller Nicorex Baltic destroy 19,000 bottles of e-cigarette liquid worth €135 000, as the packaging size did not meet the new requirements.

The liquids were actually in order, had undergone laboratory testing and met the new requirements, but their packaging did not have the necessary warnings on them and the boxes did not contain instructions.

Nicorex said that the transition period allowed by the government was too short, as the shelf life of the liquids was two years, but the length of the transition period only one year.

At the same time, Nicorex welcomed the requirement that the liquids have to undergo laboratory testing and that both the equipment and liquids must be registered in a single European database.

Nicorex described the restrictions concerning the size of packaging as unreasonable, as they increased the ecological footprint.

The transition period under the new tobacco law arising from the European tobacco products directive will end on May 20, after which the stricter requirements will apply to e-cigarettes in full.

Liquids can't be sold in containers bigger than 10 ml, they can't contain more nicotine than 20 milligrams per milliliter, and the vaporizer can't be bigger than 2 ml.

The packaging needs to include a leaflet, instructions, a batch number, a date, and a warning that nicotine is an addictive substance.

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

The entering into force of the requirements of the European tobacco products directive in Estonia made e-cigarette seller Nicorex Baltic destroy 19,000 bottles of e-cigarette liquid worth €135 000, as the packaging size did not meet the new requirements.

The liquids were actually in order, had undergone laboratory testing and met the new requirements, but their packaging did not have the necessary warnings on them and the boxes did not contain instructions.

Nicorex said that the transition period allowed by the government was too short, as the shelf life of the liquids was two years, but the length of the transition period only one year.

At the same time, Nicorex welcomed the requirement that the liquids have to undergo laboratory testing and that both the equipment and liquids must be registered in a single European database.

Nicorex described the restrictions concerning the size of packaging as unreasonable, as they increased the ecological footprint.

The transition period under the new tobacco law arising from the European tobacco products directive will end on May 20, after which the stricter requirements will apply to e-cigarettes in full.

Liquids can't be sold in containers bigger than 10 ml, they can't contain more nicotine than 20 milligrams per milliliter, and the vaporizer can't be bigger than 2 ml.

The packaging needs to include a leaflet, instructions, a batch number, a date, and a warning that nicotine is an addictive substance.

An electronic cigarette is a battery-powered vaporizer.[1] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[3] When the user pushes a button,[4] or (in some variations) activates a pressure sensor by inhaling, the heating element then atomizes the liquid solution[5] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[7] The aerosol provides a flavor and feel similar to tobacco smoking.[1]

There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] Most cigalikes look like cigarettes but there is some variation in size.[11] Second generation devices are larger overall and look less like tobacco cigarettes.[12] Third generation devices include mechanical mods and variable voltage devices.[10] The fourth generation includes Sub ohm tanks and temperature control devices.[13] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[15]

A later-generation box mod e-cigarette. Image courtesy of Ecigclick

An e-cigarette is a handheld battery-powered vaporizer that simulates smoking, but without tobacco combustion.[1] Once the user inhales, the airflow activates the pressure sensor, and then the heating element atomizes the liquid solution.[5] Most devices have a manual push-button switch to turn them on or off.[16] E-cigarettes do not turn on by trying to "light" the device with a flame.[4] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] However, variable voltage devices can raise the temperature.[17] A glycerin-only liquid vaporizes at a higher temperature than a propylene glycol-glycerin liquid.[17] Rather than cigarette smoke, the user inhales an aerosol, commonly but inaccurately called vapor.[7] E-cigarettes do not create vapor between puffs.[18]

Vaping is different than tobacco smoking, but there are some similarities with their behavioral habits, including the hand-to-mouth action and a vapor that looks like cigarette smoke.[1] E-cigarettes provide a flavor and feel similar to smoking.[1] A noticeable difference between the traditional cigarette and the e-cigarette is sense of touch.[1] A traditional cigarette is smooth and light but an e-cigarette is rigid, cold and slightly heavier.[1] Since e-cigarettes are more complex than traditional cigarettes, a learning curve is needed to use them correctly.[19]

Compared to traditional cigarettes, the general e-cigarette puff time is much longer, and requires a more forceful suction than a regular cigarette.[20] The volume of vapor created by e-cigarette devices in 2012 declined with vaping.[1] Thus, to create the same volume of vapor increasing puff force is needed.[1] Later-generation e-cigarettes with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[21] Many e-cigarette versions include a voltage potentiometer to adjust the volume of vapor created.[4] The amount of vapor produced is controlled by the power from the battery, which has led some users to adjust their devices to increase battery power.[6]

An ordinary cigarette compared to a "cigalike" e-cigarette

E-cigarettes are usually approximately cylindrical, with many variations: pen-styles, tank-styles etc.[22] Some e-cigarettes look like traditional cigarettes, but others do not.[19] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8]

The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] The only exception to this are mechanical e-cigarettes (mods) which contain no electronics and the circuit is closed by using a mechanical action switch.[23] E-cigarettes are sold in disposable or reusable variants.[8] Disposable e-cigarettes are discarded once the liquid in the cartridge is used up, while rechargeable e-cigarettes may be used indefinitely.[24] A disposable e-cigarette lasts to around 400 puffs.[25] Reusable e-cigarettes are refilled by hand or exchanged for pre-filled cartridges, and general cleaning is required.[4] A wide range of disposable and reusable e-cigarettes exist.[26] Disposable e-cigarettes are offered for a few dollars, and higher-priced reusable e-cigarettes involve an up-front investment for a starter kit.[19] Some e-cigarettes have a LED at the tip to resemble the glow of burning tobacco.[21] The LED may also indicate the battery status.[1] The LED is not generally used in personal vaporizers or mods.[2]

First-generation e-cigarettes usually simulated smoking implements, such as cigarettes or cigars, in their use and appearance.[10] Later-generation e-cigarettes often called mods, PVs (personal vaporizer) or APVs (advanced personal vaporizer) have an increased nicotine-dispersal performance,[10] house higher capacity batteries, and come in various shapes such as metal tubes and boxes.[27] They contain silver, steel, metals, ceramics, plastics, fibers, aluminum, rubber and spume, and lithium batteries.[28] A growing subclass of vapers called cloud-chasers configure their atomizers to produce large amounts of vapor by using low-resistance heating coils.[29] This practice is known as cloud-chasing.[30] Many e-cigarettes are made of standardized replaceable parts that are interchangeable between brands.[31] A wide array of component combinations exists.[32] Many e-cigarettes are sold with a USB charger.[33] E-cigarettes that resemble pens or USB memory sticks are also sold for those who may want to use the device unobtrusively.[34]

As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9]

Various types of e-cigarettes.

First-generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] The three parts of a cigalike e-cigarette initially were a cartridge, an atomizer, and a battery.[35] A cigalike e-cigarette currently contains a cartomizer (cartridge atomizer), which is connected to a battery.[35] Most cigalikes look like cigarettes but there is some variation in size.[35]

They may be a single unit comprising a battery, coil and filling saturated with e-juice in a single tube to be used and discarded after the battery or e-liquid is depleted.[10] They may also be a reusable device with a battery and cartridge called a cartomizer.[12] The cartomizer cartridge can be separated from the battery so the battery can be charged and the empty cartomizer replaced when the e-juice runs out.[10]

The battery section may contain an electronic airflow sensor triggered by drawing breath through the device.[12] Other models use a power button that must be held during operation.[12] An LED in the power button or on the end of the device may also show when the device is vaporizing.[36]

Charging is commonly accomplished with a USB charger that attaches to the battery.[37] Some manufacturers also have a cigarette pack-shaped portable charging case (PCC), which contains a larger battery capable of recharging the individual e-cigarette batteries.[38] Reusable devices can come in a kit that contains a battery, a charger, and at least one cartridge.[38] Varying nicotine concentrations are available and nicotine delivery to the user also varies based on different cartomizers, e-juice mixtures, and power supplied by the battery.[22]

These manufacturing differences affect the way e-cigarettes convert the liquid solution to an aerosol, and thus the levels of ingredients, that are delivered to the user and the surrounding air for any given liquid.[22] First-generation e-cigarettes use lower voltages, around 3.7 V.[39]

Second-generation PV.

Second generation devices tend to be used by people with more experience.[12] They are larger overall and look less like tobacco cigarettes.[12] They usually consist of two sections, basically a tank and a separate battery. Their batteries have higher capacity, and are not removable.[10] Being rechargeable, they use a USB charger that attaches to the battery with a threaded connector. Some batteries have a "passthrough" feature so they can be used even while they are charging.[40][41]

Second-generation e-cigarettes commonly use a tank or a "clearomizer".[12] Clearomizer tanks are meant to be refilled with e-juice, while cartomizers are not.[10] Because they're refillable and the battery is rechargeable, their cost of operation is lower.[10] Hovever, they can also use cartomizers, which are pre-filled only.[10]

Some cheaper battery sections use a microphone that detects the turbulence of the air passing through to activate the device when the user inhales.[42] Other batteries like the eGo style can use an integrated circuit, as well as a button for manual activation. The LED shows battery status.[42] The power button can also switch off the battery so it is not activated accidentally.[43] Second generation e-cigarettes may have lower voltages, around 3.7 V.[39] However, adjustable-voltage devices can be set between 3 V and 6 V.[44]

Third-generation PV.

The third-generation includes mechanical mods and variable voltage devices.[45][46] Battery sections are commonly called "mods," referencing their past when user modification was common.[10] Mechanical mods do not contain integrated circuits.[46] They are commonly cylindrical or box-shaped, and typical housing materials are wood, aluminium, stainless steel, or brass.[47] A larger "box mod" can hold bigger and sometimes multiple batteries.[47]

Mechanical mods and variable devices use larger batteries than those found in previous generations.[48] Common battery sizes used are 18350, 18490, 18500 and 18650.[49] The battery is often removable,[46] so it can be changed when depleted. The battery must be removed and charged externally.[46]

Variable devices permit setting wattage, voltage, or both.[40][46] These often have a USB connector for recharging; some can be used while charging, called a "passthrough" feature.[40][50] Mechanical mods do not contain integrated circuits.[46]

The power section may include additional options such as screen readout, support for a wide range of internal batteries, and compatibility with different types of atomizers.[12] Third-generation devices can have rebuildable atomizers with different wicking materials.[10][12] These rebuildables use handmade coils that can be installed in the atomizer to increase vapor production.[48] Hardware in this generation is sometimes modified to increase power or flavor.[51]

The larger battery sections used also allow larger tanks to be attached that can hold more e-liquid.[47] Recent devices can go up to 8 V, which can heat the e-liquid significantly more than earlier generations.[39]

A fourth-generation e-cigarette became available in the U.S. in 2014.[21] Fourth-generation e-cigarettes can be made from stainless steel and pyrex glass, and contain very little plastics.[13] Included in the fourth-generation are Sub ohm tanks and temperature control devices.[13]

An e-cigarette atomizer with the coil (heating element) in view.

An atomizer comprises a small heating element that vaporizes e-liquid and a wicking material that draws liquid onto the coil.[3] Along with a battery and e-liquid the atomizer is the main component of every personal vaporizer.[12] A small length of resistance wire is coiled around the wicking material and connected to the integrated circuit, or in the case of mechanical devices, the atomizer is connected directly to the battery through either a 510, 808, or ego threaded connector.[52] 510 being the most common.[52] When activated, the resistance wire coil heats up and vaporizes the liquid, which is then inhaled by the user.[53]

The electrical resistance of the coil, the voltage output of the device, the airflow of the atomizer and the efficiency of the wick all affect the vapor coming from the atomizer.[54] They also affect the vapor quantity or volume yielded.[54]

Atomizer coils made of kanthal usually have resistances that vary from 0.4Ω (ohms) to 2.8Ω.[54] Coils of lower ohms have increased vapor production but could risk fire and dangerous battery failures if the user is not knowledgeable enough about electrical principles and how they relate to battery safety.[55]

The cartomizer was invented in 2007, integrating the heating coil into the liquid chamber.[57] A "cartomizer" (a portmanteau of cartridge and atomizer.[58]) or "carto" consists of an atomizer surrounded by a liquid-soaked poly-foam that acts as an e-liquid holder.[3] They can have up to 3 coils and each coil will increase vapor production.[3] The cartomizer is usually discarded when the e-liquid starts to taste burnt, which usually happens when the e-cigarette is activated with a dry coil or when the cartomizer gets consistently flooded (gurgling) because of sedimentation of the wick.[3] Most cartomizers are refillable even if not advertised as such.[3][59]

Cartomizers can be used on their own or in conjunction with a tank that allows more e-liquid capacity.[3] The portmanteau word "cartotank" has been coined for this.[60] When used in a tank, the cartomizer is inserted in a plastic, glass or metal tube and holes or slots have to be punched on the sides of the cartomizer so liquid can reach the coil.[3]

eGo style e-cigarette with a top-coil clearomizer. Silica fibers are hanging down freely inside of the tank, drawing e-liquid by capillary action to the coil that is located directly under the mouthpiece.

The clearomizer was invented in 2009 that originated from the cartomizer design.[57] It contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component.[57] This allows the user to monitor the liquid level in the device.[57] Clearomizers or "clearos", are like cartotanks, in that an atomizer is inserted into the tank.[61] There are different wicking systems used inside clearomizers.[3] Some rely on gravity to bring the e-liquid to the wick and coil assembly (bottom coil clearomizers for example) and others rely on capillary action or to some degree the user agitating the e-liquid while handling the clearomizer (top coil clearomizers).[3][62] The coil and wicks are typically inside a prefabricated assembly or "head" that is replaceable by the user.[63]

Clearomizers are made with adjustable air flow control.[64] Tanks can be plastic or borosilicate glass.[65] Some flavors of e-juice have been known to damage plastic clearomizer tanks.[65]

Box mod e-cigarette fitted with a rebuildable dripping atomizer (RDA). A view of the RDA deck showing the wicks and coils, juice is dripped into a hopper where the wicks rest as well as atop the coil assembly.

A rebuildable atomizer or an RBA is an atomizer that allows the user to assemble or "build" the wick and coil themselves instead of replacing them with off-the-shelf atomizer "heads".[10] They are generally considered advanced devices.[66] They also allow the user to build atomizers at any desired electrical resistance.[10]

These atomizers are divided into two main categories; rebuildable tank atomizers (RTAs) and rebuildable dripping atomizers (RDAs).[67]

Rebuildable tank atomizers (RTAs) have a tank to hold liquid that is absorbed by the wick.[68] They can hold up to 4ml of e-liquid.[69] The tank can be either plastic, glass, or metal.[65] One form of tank atomizers was the Genesis style atomizers.[68] They can use ceramic wicks, stainless steel mesh or rope for wicking material.[68] The steel wick must be oxidized to prevent arcing of the coil.[68] Another type is the Sub ohm tank.[69] These tanks have rebuildabe or RBA kits.[69] They can also use coilheads of 0.2ohm 0.4hom and 0.5ohm.[69] These coilheads can have stainless steel coils.[70]

Rebuildable dripping atomizers (RDAs) are atomizers where the e-juice is dripped directly onto the coil and wick.[71] The common nicotine strength of e-liquids used in RDA's is 3 mg and 6 mg.[71] Liquids used in RDA's tend to have more vegetable glycerin.[71] They typically consist only of an atomizer "building deck", commonly with three posts with holes drilled in them, which can accept one or more coils.[51] The user needs to manually keep the atomizer wet by dripping liquid on the bare wick and coil assembly, hence their name.[71]

Kanthal wire is commonly used in both RDA's and RTA's.[71] They can also use nickel wire or titanium wire for temperature control.[71]

Variable devices are variable wattage, variable voltage or both.[40][46] Variable power and/or variable voltage have a electronic chip allowing the user to adjust the power applied to the heating element.[12][46] The amount of power applied to the coil affects the heat produced, thus changing the vapor output.[12][32] Greater heat from the coil increases vapor production.[32] Variable power devices monitor the coil's resistance and automatically adjust the voltage to apply the user-specified level of power to the coil.[72] Recent devices can go up to 8 V.[39]

They are often rectangular but can also be cylindrical.[47] They usually have a screen to show information such as voltage, power, and resistance of the coil.[73] To adjust the settings, the user presses buttons or rotates a dial to turn the power up or down.[32] Some of these devices include additional settings through their menu system such as: atomizer resistance meter, remaining battery voltage, puff counter, and power-off or lock.[74] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[4] Smaller devices contain smaller batteries and are easier to carry but typically require more repeated recharging.[4] Some e-cigarettes use a long lasting rechargeable battery, a non-rechargeable battery or a replaceable battery that is either rechargeable or non-rechargeable for power.[26] Some companies offer portable chargeable cases to recharge e-cigarettes.[26] Nickel-cadmium (NiCad), nickel metal-hydride (NiMh), lithium ion (Li-ion), alkaline and lithium polymer (Li-poly), and lithium manganese (LiMn) batteries have been used for the e-cigarettes power source.[26]

PV with variable and regulated power offering battery protection.

Temperature control devices allow the user to set the temperature.[71] There is a predictable change to the resistance of a coil when it is heated.[75] The resistance changes are different for different types of wires, and must have a high temperature coefficient of resistance.[75] Temperature control is done by detecting that resistance change to estimate the temperature and adjusting the voltage to the coil to match that estimate.[76]

Nickel, titanium, NiFe alloys, and certain grades of stainless steel are common materials used for wire in temperature control.[71] The most common wire used, kanthal, cannot be used because it has a stable resistance regardless of the coil temperature.[75] Nickel was the first wire used because of it has the highest coefficient of the common metals.[75]

Mechanical PV with a rebuildable atomizer.

The temperature can be adjusted in Celsius or Fahrenheit.[77] The DNA40 and SX350J are common control boards used in temperature control devices.[78] Temperature control can stop dry wicks from burning, or e-liquid overheating.[78]

Mechanical PVs or mechanical "mods", often called "mechs", are devices without integrated circuits, electronic battery protection, or voltage regulation.[46] They are activated by a switch.[71] They rely on the natural voltage output of the battery and the metal that the mod is made of often is used as part of the circuit itself.[79]

The term "mod" was originally used instead of "modification".[10] Users would modify existing hardware to get better performance, and as an alternative to the e-cigarettes that looked like traditional cigarettes.[32] Users would also modify other unrelated items like flashlights as battery compartments to power atomizers.[32][47] The word mod is often used to describe most personal vaporizers.[3]

Mechanical PVs have no power regulation and are unprotected.[71] Because of this ensuring that the battery does not over-discharge and that the resistance of the atomizer requires amperage within the safety limits of the battery is the responsibility of the user.[79]

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

The entering into force of the requirements of the European tobacco products directive in Estonia made e-cigarette seller Nicorex Baltic destroy 19,000 bottles of e-cigarette liquid worth €135 000, as the packaging size did not meet the new requirements.

The liquids were actually in order, had undergone laboratory testing and met the new requirements, but their packaging did not have the necessary warnings on them and the boxes did not contain instructions.

Nicorex said that the transition period allowed by the government was too short, as the shelf life of the liquids was two years, but the length of the transition period only one year.

At the same time, Nicorex welcomed the requirement that the liquids have to undergo laboratory testing and that both the equipment and liquids must be registered in a single European database.

Nicorex described the restrictions concerning the size of packaging as unreasonable, as they increased the ecological footprint.

The transition period under the new tobacco law arising from the European tobacco products directive will end on May 20, after which the stricter requirements will apply to e-cigarettes in full.

Liquids can't be sold in containers bigger than 10 ml, they can't contain more nicotine than 20 milligrams per milliliter, and the vaporizer can't be bigger than 2 ml.

The packaging needs to include a leaflet, instructions, a batch number, a date, and a warning that nicotine is an addictive substance.

Safety of electronic cigarettes

UK

Disassembled parts of a first generation e-cigarette. A. LED light cover B. battery (also houses circuitry) C. atomizer (heating element) D. cartridge (mouthpiece) Parts of a second generation e-cigarette. An electronic cigarette is a battery-powered vaporizer.[1] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[3] When the user pushes a button,[4] or (in some variations) activates a pressure sensor by inhaling, the heating element then atomizes the liquid solution[5] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[7] The aerosol provides a flavor and feel similar to tobacco smoking.[1] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] Most cigalikes look like cigarettes but there is some variation in size.[11] Second generation devices are larger overall and look less like tobacco cigarettes.[12] Third generation devices include mechanical mods and variable voltage devices.[10] The fourth generation includes Sub ohm tanks and temperature control devices.[13] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[15] A later-generation box mod e-cigarette. Image courtesy of Ecigclick An e-cigarette is a handheld battery-powered vaporizer that simulates smoking, but without tobacco combustion.[1] Once the user inhales, the airflow activates the pressure sensor, and then the heating element atomizes the liquid solution.[5] Most devices have a manual push-button switch to turn them on or off.[16] E-cigarettes do not turn on by trying to "light" the device with a flame.[4] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] However, variable voltage devices can raise the temperature.[17] A glycerin-only liquid vaporizes at a higher temperature than a propylene glycol-glycerin liquid.[17] Rather than cigarette smoke, the user inhales an aerosol, commonly but inaccurately called vapor.[7] E-cigarettes do not create vapor between puffs.[18] Vaping is different than tobacco smoking, but there are some similarities with their behavioral habits, including the hand-to-mouth action and a vapor that looks like cigarette smoke.[1] E-cigarettes provide a flavor and feel similar to smoking.[1] A noticeable difference between the traditional cigarette and the e-cigarette is sense of touch.[1] A traditional cigarette is smooth and light but an e-cigarette is rigid, cold and slightly heavier.[1] Since e-cigarettes are more complex than traditional cigarettes, a learning curve is needed to use them correctly.[19] Compared to traditional cigarettes, the general e-cigarette puff time is much longer, and requires a more forceful suction than a regular cigarette.[20] The volume of vapor created by e-cigarette devices in 2012 declined with vaping.[1] Thus, to create the same volume of vapor increasing puff force is needed.[1] Later-generation e-cigarettes with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[21] Many e-cigarette versions include a voltage potentiometer to adjust the volume of vapor created.[4] The amount of vapor produced is controlled by the power from the battery, which has led some users to adjust their devices to increase battery power.[6] An ordinary cigarette compared to a "cigalike" e-cigarette E-cigarettes are usually approximately cylindrical, with many variations: pen-styles, tank-styles etc.[22] Some e-cigarettes look like traditional cigarettes, but others do not.[19] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] The only exception to this are mechanical e-cigarettes (mods) which contain no electronics and the circuit is closed by using a mechanical action switch.[23] E-cigarettes are sold in disposable or reusable variants.[8] Disposable e-cigarettes are discarded once the liquid in the cartridge is used up, while rechargeable e-cigarettes may be used indefinitely.[24] A disposable e-cigarette lasts to around 400 puffs.[25] Reusable e-cigarettes are refilled by hand or exchanged for pre-filled cartridges, and general cleaning is required.[4] A wide range of disposable and reusable e-cigarettes exist.[26] Disposable e-cigarettes are offered for a few dollars, and higher-priced reusable e-cigarettes involve an up-front investment for a starter kit.[19] Some e-cigarettes have a LED at the tip to resemble the glow of burning tobacco.[21] The LED may also indicate the battery status.[1] The LED is not generally used in personal vaporizers or mods.[2] First-generation e-cigarettes usually simulated smoking implements, such as cigarettes or cigars, in their use and appearance.[10] Later-generation e-cigarettes often called mods, PVs (personal vaporizer) or APVs (advanced personal vaporizer) have an increased nicotine-dispersal performance,[10] house higher capacity batteries, and come in various shapes such as metal tubes and boxes.[27] They contain silver, steel, metals, ceramics, plastics, fibers, aluminum, rubber and spume, and lithium batteries.[28] A growing subclass of vapers called cloud-chasers configure their atomizers to produce large amounts of vapor by using low-resistance heating coils.[29] This practice is known as cloud-chasing.[30] Many e-cigarettes are made of standardized replaceable parts that are interchangeable between brands.[31] A wide array of component combinations exists.[32] Many e-cigarettes are sold with a USB charger.[33] E-cigarettes that resemble pens or USB memory sticks are also sold for those who may want to use the device unobtrusively.[34] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] Various types of e-cigarettes. First-generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] The three parts of a cigalike e-cigarette initially were a cartridge, an atomizer, and a battery.[35] A cigalike e-cigarette currently contains a cartomizer (cartridge atomizer), which is connected to a battery.[35] Most cigalikes look like cigarettes but there is some variation in size.[35] They may be a single unit comprising a battery, coil and filling saturated with e-juice in a single tube to be used and discarded after the battery or e-liquid is depleted.[10] They may also be a reusable device with a battery and cartridge called a cartomizer.[12] The cartomizer cartridge can be separated from the battery so the battery can be charged and the empty cartomizer replaced when the e-juice runs out.[10] The battery section may contain an electronic airflow sensor triggered by drawing breath through the device.[12] Other models use a power button that must be held during operation.[12] An LED in the power button or on the end of the device may also show when the device is vaporizing.[36] Charging is commonly accomplished with a USB charger that attaches to the battery.[37] Some manufacturers also have a cigarette pack-shaped portable charging case (PCC), which contains a larger battery capable of recharging the individual e-cigarette batteries.[38] Reusable devices can come in a kit that contains a battery, a charger, and at least one cartridge.[38] Varying nicotine concentrations are available and nicotine delivery to the user also varies based on different cartomizers, e-juice mixtures, and power supplied by the battery.[22] These manufacturing differences affect the way e-cigarettes convert the liquid solution to an aerosol, and thus the levels of ingredients, that are delivered to the user and the surrounding air for any given liquid.[22] First-generation e-cigarettes use lower voltages, around 3.7 V.[39] Second-generation PV. Second generation devices tend to be used by people with more experience.[12] They are larger overall and look less like tobacco cigarettes.[12] They usually consist of two sections, basically a tank and a separate battery. Their batteries have higher capacity, and are not removable.[10] Being rechargeable, they use a USB charger that attaches to the battery with a threaded connector. Some batteries have a "passthrough" feature so they can be used even while they are charging.[40][41] Second-generation e-cigarettes commonly use a tank or a "clearomizer".[12] Clearomizer tanks are meant to be refilled with e-juice, while cartomizers are not.[10] Because they're refillable and the battery is rechargeable, their cost of operation is lower.[10] Hovever, they can also use cartomizers, which are pre-filled only.[10] Some cheaper battery sections use a microphone that detects the turbulence of the air passing through to activate the device when the user inhales.[42] Other batteries like the eGo style can use an integrated circuit, as well as a button for manual activation. The LED shows battery status.[42] The power button can also switch off the battery so it is not activated accidentally.[43] Second generation e-cigarettes may have lower voltages, around 3.7 V.[39] However, adjustable-voltage devices can be set between 3 V and 6 V.[44] Third-generation PV. The third-generation includes mechanical mods and variable voltage devices.[45][46] Battery sections are commonly called "mods," referencing their past when user modification was common.[10] Mechanical mods do not contain integrated circuits.[46] They are commonly cylindrical or box-shaped, and typical housing materials are wood, aluminium, stainless steel, or brass.[47] A larger "box mod" can hold bigger and sometimes multiple batteries.[47] Mechanical mods and variable devices use larger batteries than those found in previous generations.[48] Common battery sizes used are 18350, 18490, 18500 and 18650.[49] The battery is often removable,[46] so it can be changed when depleted. The battery must be removed and charged externally.[46] Variable devices permit setting wattage, voltage, or both.[40][46] These often have a USB connector for recharging; some can be used while charging, called a "passthrough" feature.[40][50] Mechanical mods do not contain integrated circuits.[46] The power section may include additional options such as screen readout, support for a wide range of internal batteries, and compatibility with different types of atomizers.[12] Third-generation devices can have rebuildable atomizers with different wicking materials.[10][12] These rebuildables use handmade coils that can be installed in the atomizer to increase vapor production.[48] Hardware in this generation is sometimes modified to increase power or flavor.[51] The larger battery sections used also allow larger tanks to be attached that can hold more e-liquid.[47] Recent devices can go up to 8 V, which can heat the e-liquid significantly more than earlier generations.[39] A fourth-generation e-cigarette became available in the U.S. in 2014.[21] Fourth-generation e-cigarettes can be made from stainless steel and pyrex glass, and contain very little plastics.[13] Included in the fourth-generation are Sub ohm tanks and temperature control devices.[13] An e-cigarette atomizer with the coil (heating element) in view. An atomizer comprises a small heating element that vaporizes e-liquid and a wicking material that draws liquid onto the coil.[3] Along with a battery and e-liquid the atomizer is the main component of every personal vaporizer.[12] A small length of resistance wire is coiled around the wicking material and connected to the integrated circuit, or in the case of mechanical devices, the atomizer is connected directly to the battery through either a 510, 808, or ego threaded connector.[52] 510 being the most common.[52] When activated, the resistance wire coil heats up and vaporizes the liquid, which is then inhaled by the user.[53] The electrical resistance of the coil, the voltage output of the device, the airflow of the atomizer and the efficiency of the wick all affect the vapor coming from the atomizer.[54] They also affect the vapor quantity or volume yielded.[54] Atomizer coils made of kanthal usually have resistances that vary from 0.4Ω (ohms) to 2.8Ω.[54] Coils of lower ohms have increased vapor production but could risk fire and dangerous battery failures if the user is not knowledgeable enough about electrical principles and how they relate to battery safety.[55] Wicking materials vary from one atomizer to another.[56] "Rebuildable" or "do it yourself" atomizers can use silica, cotton, rayon, porous ceramic, hemp, bamboo yarn, oxidized stainless steel mesh and even wire rope cables as wicking materials.[56] A 45mm length, extra-long cartomizer. The cartomizer was invented in 2007, integrating the heating coil into the liquid chamber.[57] A "cartomizer" (a portmanteau of cartridge and atomizer.[58]) or "carto" consists of an atomizer surrounded by a liquid-soaked poly-foam that acts as an e-liquid holder.[3] They can have up to 3 coils and each coil will increase vapor production.[3] The cartomizer is usually discarded when the e-liquid starts to taste burnt, which usually happens when the e-cigarette is activated with a dry coil or when the cartomizer gets consistently flooded (gurgling) because of sedimentation of the wick.[3] Most cartomizers are refillable even if not advertised as such.[3][59] Cartomizers can be used on their own or in conjunction with a tank that allows more e-liquid capacity.[3] The portmanteau word "cartotank" has been coined for this.[60] When used in a tank, the cartomizer is inserted in a plastic, glass or metal tube and holes or slots have to be punched on the sides of the cartomizer so liquid can reach the coil.[3] eGo style e-cigarette with a top-coil clearomizer. Silica fibers are hanging down freely inside of the tank, drawing e-liquid by capillary action to the coil that is located directly under the mouthpiece. The clearomizer was invented in 2009 that originated from the cartomizer design.[57] It contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component.[57] This allows the user to monitor the liquid level in the device.[57] Clearomizers or "clearos", are like cartotanks, in that an atomizer is inserted into the tank.[61] There are different wicking systems used inside clearomizers.[3] Some rely on gravity to bring the e-liquid to the wick and coil assembly (bottom coil clearomizers for example) and others rely on capillary action or to some degree the user agitating the e-liquid while handling the clearomizer (top coil clearomizers).[3][62] The coil and wicks are typically inside a prefabricated assembly or "head" that is replaceable by the user.[63] Clearomizers are made with adjustable air flow control.[64] Tanks can be plastic or borosilicate glass.[65] Some flavors of e-juice have been known to damage plastic clearomizer tanks.[65] Box mod e-cigarette fitted with a rebuildable dripping atomizer (RDA). A view of the RDA deck showing the wicks and coils, juice is dripped into a hopper where the wicks rest as well as atop the coil assembly. A rebuildable atomizer or an RBA is an atomizer that allows the user to assemble or "build" the wick and coil themselves instead of replacing them with off-the-shelf atomizer "heads".[10] They are generally considered advanced devices.[66] They also allow the user to build atomizers at any desired electrical resistance.[10] These atomizers are divided into two main categories; rebuildable tank atomizers (RTAs) and rebuildable dripping atomizers (RDAs).[67] Rebuildable tank atomizers (RTAs) have a tank to hold liquid that is absorbed by the wick.[68] They can hold up to 4ml of e-liquid.[69] The tank can be either plastic, glass, or metal.[65] One form of tank atomizers was the Genesis style atomizers.[68] They can use ceramic wicks, stainless steel mesh or rope for wicking material.[68] The steel wick must be oxidized to prevent arcing of the coil.[68] Another type is the Sub ohm tank.[69] These tanks have rebuildabe or RBA kits.[69] They can also use coilheads of 0.2ohm 0.4hom and 0.5ohm.[69] These coilheads can have stainless steel coils.[70] Rebuildable dripping atomizers (RDAs) are atomizers where the e-juice is dripped directly onto the coil and wick.[71] The common nicotine strength of e-liquids used in RDA's is 3 mg and 6 mg.[71] Liquids used in RDA's tend to have more vegetable glycerin.[71] They typically consist only of an atomizer "building deck", commonly with three posts with holes drilled in them, which can accept one or more coils.[51] The user needs to manually keep the atomizer wet by dripping liquid on the bare wick and coil assembly, hence their name.[71] Kanthal wire is commonly used in both RDA's and RTA's.[71] They can also use nickel wire or titanium wire for temperature control.[71] Variable devices are variable wattage, variable voltage or both.[40][46] Variable power and/or variable voltage have a electronic chip allowing the user to adjust the power applied to the heating element.[12][46] The amount of power applied to the coil affects the heat produced, thus changing the vapor output.[12][32] Greater heat from the coil increases vapor production.[32] Variable power devices monitor the coil's resistance and automatically adjust the voltage to apply the user-specified level of power to the coil.[72] Recent devices can go up to 8 V.[39] They are often rectangular but can also be cylindrical.[47] They usually have a screen to show information such as voltage, power, and resistance of the coil.[73] To adjust the settings, the user presses buttons or rotates a dial to turn the power up or down.[32] Some of these devices include additional settings through their menu system such as: atomizer resistance meter, remaining battery voltage, puff counter, and power-off or lock.[74] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[4] Smaller devices contain smaller batteries and are easier to carry but typically require more repeated recharging.[4] Some e-cigarettes use a long lasting rechargeable battery, a non-rechargeable battery or a replaceable battery that is either rechargeable or non-rechargeable for power.[26] Some companies offer portable chargeable cases to recharge e-cigarettes.[26] Nickel-cadmium (NiCad), nickel metal-hydride (NiMh), lithium ion (Li-ion), alkaline and lithium polymer (Li-poly), and lithium manganese (LiMn) batteries have been used for the e-cigarettes power source.[26] PV with variable and regulated power offering battery protection. Temperature control devices allow the user to set the temperature.[71] There is a predictable change to the resistance of a coil when it is heated.[75] The resistance changes are different for different types of wires, and must have a high temperature coefficient of resistance.[75] Temperature control is done by detecting that resistance change to estimate the temperature and adjusting the voltage to the coil to match that estimate.[76] Nickel, titanium, NiFe alloys, and certain grades of stainless steel are common materials used for wire in temperature control.[71] The most common wire used, kanthal, cannot be used because it has a stable resistance regardless of the coil temperature.[75] Nickel was the first wire used because of it has the highest coefficient of the common metals.[75] Mechanical PV with a rebuildable atomizer. The temperature can be adjusted in Celsius or Fahrenheit.[77] The DNA40 and SX350J are common control boards used in temperature control devices.[78] Temperature control can stop dry wicks from burning, or e-liquid overheating.[78] Mechanical PVs or mechanical "mods", often called "mechs", are devices without integrated circuits, electronic battery protection, or voltage regulation.[46] They are activated by a switch.[71] They rely on the natural voltage output of the battery and the metal that the mod is made of often is used as part of the circuit itself.[79] The term "mod" was originally used instead of "modification".[10] Users would modify existing hardware to get better performance, and as an alternative to the e-cigarettes that looked like traditional cigarettes.[32] Users would also modify other unrelated items like flashlights as battery compartments to power atomizers.[32][47] The word mod is often used to describe most personal vaporizers.[3] Mechanical PVs have no power regulation and are unprotected.[71] Because of this ensuring that the battery does not over-discharge and that the resistance of the atomizer requires amperage within the safety limits of the battery is the responsibility of the user.[79]

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

(Redirected from Health effects of electronic cigarettes)

The safetyofelectronic cigarettes is uncertain.[1][2][3] There is little data about their safety, and considerable variability among e-cigarettes and in their liquid ingredients[4] and thus the contents of the aerosol delivered to the user.[5] Reviews on the safety of e-cigarettes have reached significantly different conclusions.[6] A 2014 World Health Organization (WHO) report cautioned about potential risks of using e-cigarettes.[7] Regulated US Food and Drug Administration (FDA) products such as nicotine inhalers are likely safer than e-cigarettes,.[8] A systematic review suggests that e-cigarettes are less harmful than smoking and since they contain no tobacco and do not involve combustion, users may avoid several harmful constituents usually found in tobacco smoke.[9][10][11] However, e-cigarettes cannot be considered harmless.[12]

E-cigarettes have been found to reduce lung and myocardial function, increase inflammation, and have toxic content including carcinogens, but to a much lower extent than combustible cigarettes in virtually all cases.[3][13] The long-term effects of e-cigarette use are unknown.[13][14][15] A 2015 study found serious adverse events related to e-cigarettes were hypotension, seizure, chest pain, rapid heartbeat, disorientation, and congestive heart failure but it was unclear to the degree they were the result of e-cigarettes.[16] Less serious adverse effects may include abdominal pain, headache, blurry vision,[16] throat and mouth irritation, vomiting, nausea, and coughing.[5] A 2014 WHO report said, "ENDS [electronic nicotine delivery system] use poses serious threats to adolescents and fetuses."[7] Aside from toxicity exposure in normal use, there are also risks from misuse or accidents[9] such as nicotine poisoning (especially among infants and children),[17] contact with liquid nicotine,[18] fires caused by vaporizer malfunction,[5] and explosions resulting from extended charging, unsuitable chargers, or design flaws.[9] Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.[1] There is a small risk of battery explosion in devices modified to increase battery power.[19]

The cytotoxicity of e-liquids varies,[20] and contamination with various chemicals have been detected in the liquid.[21] Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.[9] Many chemicals including carbonyl compounds such as formaldehyde can inadvertently be produced when the nichrome wire (heating element) that touches the e-liquid is heated and chemically reacted with the liquid.[22] Normal usage of e-cigarettes,[23] and reduced voltage (3.0 V[24]) devices generate very low levels of formaldehyde.[22] Later-generation e-cigarettes used with higher power may generate equal or higher levels of formaldehyde than compared to smoking.[14][Notes 1] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[25] A 2015 Public Health England (PHE) report found that high levels of formaldehyde only occurred in overheated "dry-puffing".[26] Users detect the "dry puff" and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[27] However, e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[19] E-cigarette users who use devices that contain nicotine are exposed to its potentially harmful effects.[24] Nicotine is associated with cardiovascular disease, potential birth defects, and poisoning.[28]In vitro studies of nicotine have associated it with cancer, but carcinogenicity has not been demonstrated in vivo.[28] There is inadequate research to demonstrate that nicotine is associated with cancer in humans.[29] The risk is probably low from the inhalation of propylene glycol and glycerin.[13] No information is available on the long-term effects of the inhalation of flavors.[21]

E-cigarettes create an aerosol that consists of fine and ultrafine particles of particulate matter, with the majority of particles in the ultrafine range.[5][30] The vapor have been found to contain flavors, propylene glycol, glycerin, nicotine, tiny amounts of toxicants, carcinogens, heavy metals, and metal nanoparticles, and other substances.[5][13] Exactly what the vapor comprises varies in composition and concentration across and within manufacturers.[24] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[31] The majority of toxic chemicals found in tobacco smoke are absent in e-cigarette vapor.[9] E-cigarette vapor contains lower concentrations of potentially toxic chemicals than with cigarette smoke.[32] Those which are present, are mostly below 1% the corresponding levels permissible by workplace safety standards.[33] But workplace safety standards do not recognize exposure to certain vulnerable groups such as people with medical ailments, children, and infants who may be exposed to second-hand vapor.[5] Concern exists that some of the mainstream vapor exhaled by e-cigarette users may be inhaled by bystanders, particularly indoors.[34] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[35] A 2014 review recommended that e-cigarettes should be regulated for consumer safety.[36] There is limited information available on the environmental issues around production, use, and disposal of e-cigarettes that use cartridges.[37]

Reviews on the safety of e-cigarettes, evaluating roughly the same studies, have reached significantly different conclusions.[6] Due to various methodological issues, severe conflicts of interest, and inconsistent research, no definite conclusions can be determined regarding the safety of e-cigarettes.[12] However, e-cigarettes cannot be regarded as harmless.[12] There is little data about their safety, and considerable variability among vaporizers and in their liquid ingredients[4] and thus the contents of the aerosol delivered to the user.[5] The health community, pharmaceutical industry, and other groups have raised concerns about the emerging phenomenon of e-cigarettes, including the unknown health risks from long-term use of e-cigarettes.[36] Concern exists that the majority of smokers attempting to quit by vaping may stop smoking but maintain nicotine intake because their long-term effects are not clear.[38] A policy statement by the American Association for Cancer Research and the American Society of Clinical Oncology has reported that "The benefits and harms must be evaluated with respect to the population as a whole, taking into account the effect on youth, adults, nonsmokers, and smokers."[17] A July 2014 World Health Organization (WHO) report cautioned about the potential risks to children and adolescents, pregnant women, and women of reproductive age regarding e-cigarette use.[7]

It is recommended the precautionary principle be used for e-cigarettes because of the long history of the tobacco crisis, in order to assess their benefits and long-term effects and to avoid another nicotine crisis.[39] A 2014 review recommended that e-cigarettes could be adequately regulated for consumer safety with existing regulations on the design of electronic products.[36] Regulation of the production and promotion of e-cigarettes may help lower some adverse effects associated with tobacco use.[34] The entrance of large US tobacco manufacturers, which are Altria Group, Reynolds American, and Lorillard, into the e-cigarette sector raises many potential public health issues.[40] Instead of encouraging quitting, the tobacco industry could market e-cigarettes as a way to get around clean indoor air laws, which promotes dual use.[40] The industry could also lead vapers to tobacco products, which would increase instead of decrease overall addiction.[40]

The health effects related to e-cigarette use is mostly unknown.[41] The health effects on intensive e-cigarette users are unknown.[14] The effect on population health from e-cigarettes is unknown.[8] Smokefree.gov, a website run by the Tobacco Control Research Branch of the National Cancer Institute to provide information to help quit smoking, stated that "Since e-cigs aren’t regulated yet, there’s no way of knowing how much nicotine is in them or what other chemicals they contain. These two things make the safety of e-cigs unclear."[42] The English National Health Service has stated, "While e-cigarettes may be safer than conventional cigarettes, we don’t yet know the long-term effects of vaping on the body."[43] The American Diabetes Association states "There is no evidence that e-cigarettes are a healthier alternative to smoking."[44] In August 2014, the Forum of International Respiratory Societies stated that e-cigarettes have not been demonstrated to be safe.[45]Health Canada has stated that, "their safety, quality, and efficacy remain unknown."[46] The National Institute on Drug Abuse stated that "There are currently no accepted measures to confirm their purity or safety, and the long-term health consequence of e-cigarette use remain unknown."[47]

Effects of vaping, compared to tobacco smoking.[48]

A 2015 Public Health England (PHE) report stated that e-cigarettes are estimated to be 95% less harmful than smoking,[49] although this estimate has been disputed.[50] In June 2014, the Royal College of Physicians stated that, "On the basis of available evidence, the RCP believes that e-cigarettes could lead to significant falls in the prevalence of smoking in the UK, prevent many deaths and episodes of serious illness, and help to reduce the social inequalities in health that tobacco smoking currently exacerbates."[51] A 2014 systematic review suggests that e-cigarettes are less harmful than smoking because there is no tobacco, no combustion, and users may avoid several harmful constituents usually found in tobacco smoke.[9] A 2014 review found that e-cigarette aerosol contains far fewer carcinogens than tobacco smoke, and concluded that e-cigarettes "impart a lower potential disease burden" than traditional cigarettes.[52] Scientific studies advocate caution before designating e-cigarettes as beneficial but vapers continue to believe they are beneficial.[53]

The American Cancer Society has stated, "The makers of e-cigarettes say that the ingredients are "safe," but this only means the ingredients have been found to be safe to eat. Inhaling a substance is not the same as swallowing it. There are questions about how safe it is to inhale some substances in the e-cigarette vapor into the lungs."[54] The Canadian Cancer Society has stated that, "A few studies have shown that there may be low levels of harmful substances in some e-cigarettes, even if they don’t have nicotine."[55] In the UK a National Institute for Health and Care Excellence (NICE) guideline did not recommend e-cigarettes as there are questions regarding the safety, efficacy, and quality of these products.[56] The US National Association of County and City Health Officials has stated, "Public health experts have expressed concern that e-cigarettes may increase nicotine addiction and tobacco use in young people."[57] No long-term studies have evaluated future tobacco use as a result of e-cigarette use.[58] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[31]

Possible adverse effects of vaping.[59]

As of 2015, the short-term and long-term effects from using e-cigarettes remain unclear.[14]Adverse effects are mostly associated with short-term use and the reported adverse effects decreased over time.[60] Long-term studies regarding the effects of constant use of e-cigarettes are unavailable.[60] The adverse effects of e-cigarettes on people with cancer is unknown.[17] A 2014 Cochrane review found no serious adverse effects reported in trials,[61] but serious events have been reported in case studies.[13]

The evidence suggests they produce less harmful effects than combusted tobacco.[11] The most frequently reported less harmful effects of vaping compared to smoking were reduced shortness of breath, reduced cough, reduced spitting, and reduced sore throat.[53] Many health benefits are associated with switching from tobacco to e-cigarettes including decreased weight gain after smoking cessation and improved exercise tolerance.[62] Vaping is possibly harmful by virtue of putting off quitting smoking, serving as a gateway to tobacco use in never-smokers or causing a return to smoking in former smokers.[63] Many people use e-cigarettes to quit smoking, but few succeed.[64] They frequently use both, which increases their health risks by using both products.[64] Quitting smoking entirely would probably have much greater beneficial effects to overall health than vaping to decrease the number of cigarettes smoked.[5]

More serious adverse effects frequently related with smoking cessation including depression, insomnia, and anxiety are uncommon with e-cigarette use.[16] A 2015 study found serious adverse events related to e-cigarettes were hypotension, seizure, chest pain, rapid heartbeat, disorientation, and congestive heart failure but it was unclear to the degree they were the result of e-cigarettes.[16] Less serious adverse effects include abdominal pain, headache, blurry vision,[16] throat and mouth irritation, vomiting, nausea, and coughing.[5] Short-term adverse effects reported most often were mouth and throat irritation, dry cough, and nausea.[60] The majority of adverse effects reported were nausea, vomiting, dizziness and oral irritation.[9] Some case reports found harms to health brought about by e-cigarettes in many countries, such as the US and in Europe; the most common effect was dryness of the mouth and throat.[22] Some e-cigarettes users experience adverse effects like throat irritation which could be the result of exposure to nicotine, nicotine solvents, or toxicants in the aerosol.[17]

The US Food and Drug Administration Center for Tobacco Products reported between 2008 and the beginning of 2012, 47 cases of adverse effects associated with e-cigarettes, of which eight were considered serious.[13] Two peer-reviewed reports of lipoid pneumonia were related to e-cigarette use, as well as two reports in the media in Spain and the UK.[41] The man from the UK reportedly died from severe lipoid pneumonia in 2011.[41] Reports to the Food and Drug Administration (FDA) for minor adverse effects identified with using e-cigarettes include headache, chest pain, nausea, and cough.[1] Major adverse effects reported to the FDA included hospitalizations for pneumonia, congestive heart failure, seizure, rapid heart rate, and burns.[1] However no direct relationship has been proven between these effects and e-cigarette use, and some of them may be due to existing health problems.[1] Many of the observed negative effects from e-cigarette use concerning the nervous system and the sensory system are probably related to nicotine overdose or withdrawal.[65] Since e-cigarettes are intended to be used repeatedly, they can conveniently be used for an extended period of time, which may contribute to increased adverse effects.[66] E-cigarettes were associated with fewer adverse effects than nicotine patches.[67]

Symptoms of nicotine poisoning related to e-cigarette calls to US poison control centers.[68]

Nicotine poisoning related to e-cigarettes include ingestion, inhalation, or absorption via the skin or eyes.[17] Accidental poisoning can result from using undiluted concentrated nicotine when mistakenly used as prepared e-liquids.[69] E-cigarettes involve accidental nicotine exposure in children.[18] Accidental exposures in pediatric patients include ingesting of e-liquids and inhaling of e-cigarette vapors.[18] Choking on e-cigarette components is a potential risk.[18] It is recommended that youth access to e-cigarettes be prohibited.[70]

Four adults died in the US and Europe, after intentionally ingesting liquid.[41] Two children, one in the US in 2014 and another in Israel in 2013, died after ingesting liquid nicotine.[71] Death from accidental nicotine poisoning is very uncommon.[72]

Calls to US poison control centers related to e-cigarette exposures involved inhalations, eye exposures, skin exposures, and ingestion, in both adults and young children.[73] Minor, moderate, and serious adverse effects involved adults and young children.[74] Minor effects correlated with e-cigarette liquid poisoning were tachycardia, tremor, chest pain and hypertension.[75] More serious effects were bradycardia, hypotension, nausea, respiratory paralysis, atrial fibrillation and dyspnea.[75] The exact correlation is not fully known between these effects and e-cigarettes.[75] 58% of e-cigarette calls to US poison control centers were related to children 5 years old or less.[74] E-cigarette calls had a greater chance to report an adverse effect and a greater chance to report a moderate or major adverse effect than traditional cigarette calls.[74] Most of the e-cigarette and traditional cigarette calls were a minor effect.[74] Severe outcomes were more than 2.5 times more frequent in children exposed to e-cigarettes and nicotine e-liquid than with traditional cigarettes.[76] E-cigarette sales were roughly equivalent to just 3.5% of traditional cigarette sales, but of the total number of e-cigarette and traditional cigarette calls to US poison control centers in December 2014, the reported e-cigarettes calls were 44%.[74]

Poison control center calls in the US related to e-cigarettes was one call per month in September 2010 to over 200 calls per month in February 2014.[77]

From September 1, 2010 to December 31, 2014, the most frequent adverse effects to e-cigarettes and e-liquid reported to US poison control centers were: Ingestion exposure resulted in vomiting, nausea, drowsy, tachycardia, or agitation;[74] inhalation/nasal exposure resulted in nausea, vomiting, dizziness, agitated, or headache;[74] ocular exposure resulted in eye irritation or pain, red eye or conjunctivitis, blurred vision, headache, or corneal abrasion;[74] multiple routes of exposure resulted in eye irritation or pain, vomiting, red eye or conjunctivitis, nausea, or cough;[74] and dermal exposure that resulted in nausea, dizziness, vomiting, headache, or tachycardia.[74] The ten most frequent adverse effects to e-cigarettes and e-liquid reported to US poison control centers were vomiting (40.4%), eye irritation or pain (20.3%), nausea (16.8%), red eye or conjunctivitis (10.5%), dizziness (7.5%), tachycardia (7.1%), drowsiness (7.1%), agitation (6.3%), headache (4.8%), and cough (4.5%).[74] In nine reported calls, exposed individuals stated the device leaked.[74] In five reported calls, individuals used e-liquid for their eyes rather than use eye drops.[74] In one reported call, an infant was given the e-liquid by an adult who thought it was the infant's medication.[74] There were also reports of choking on e-cigarette components.[18]

From January 1, 2016 and April 30, 2016, the American Association of Poison Control Centers (AAPCC) reported 623 exposures related to e-cigarettes.[64] The AAPCC reported 3,067 exposures relating to e-cigarettes and liquid nicotine in 2015, and 3,783 in 2014.[78] From September 1, 2010 to December 31, 2014, there were at least 5,970 e-cigarette calls to US poison control centers.[74] Calls to US poison control centers related to e-cigarettes increased between September 2010 to February 2014, and of the total number of cigarettes and e-cigarettes calls, e-cigarette calls increased from 0.3% to 41.7%.[67] Calls to US poison controls centers related to e-cigarette liquid poisoning increased from 1 in September 2010 to 215 for the month of February 2014.[75] E-cigarette calls was 401 for the month of April 2014.[74] The California Poison Control System reported 35 cases of e-cigarette contact from 2010 to 2012, 14 were in children and 25 were from accidental contact.[9]

Fruit flavored e-liquids.

There is a possibility that inhalation, ingestion, or skin contact can expose people to high levels of nicotine.[34] Concerns with exposure to the e-liquids include leaks or spills and contact with contaminants in the e-liquid.[79] This may be especially risky to children, pregnant women, and nursing mothers.[34] The liquid quickly absorbs into the skin.[80] The nicotine in e-liquid can be hazardous to infants.[81] Even a portion of e-liquid may be lethal to a little child.[82] An excessive amount of nicotine for a child that is capable of being fatal is 0.1–0.2 mg/kg of body weight.[34] Less than a 1 tablespoon of contact or ingestion of e-liquid can cause nausea, vomiting, cardiac arrest, seizures, or coma.[83] An accidental ingestion of only 6 mg may be lethal to children.[38][84]

Children are susceptible to ingestion due to their curiosity and desire for oral exploration.[76] E-cigarettes are packed in colorful containers[74] and children may be attracted to the flavored liquids.[58] More youth-oriented flavors include "My Birthday Cake" or "Tutti Frutti Gumballs".[71] Many nicotine cartridges and bottles of liquid are not child-resistant to stop contact or accidental ingestion of nicotine by children.[11] "Open" e-cigarette devices, with a reﬁllable tank for e-liquids, are believed to be the biggest risk to young children.[83] It is recommended that e-cigarettes be kept in a safe place, where children and pets do not have access to them.[85]

Nicotine toxicity is of concern when e-cigarette solutions are swallowed intentionally by adults as a suicidal overdose.[40] Six people attempted suicide by injecting e-liquid.[41] One adolescent attempted suicide by swallowing the e-liquid.[18] Three deaths were reported to have resulted from swallowing or injecting e-liquid containing nicotine.[41] An excessive amount of nicotine for an adult that is capable of being fatal is 0.5–1 mg/kg of body weight.[34] An oral lethal dose for adults is about 30–60 mg.[53] However the widely used human LD50 estimate of around 0.8 mg/kg was questioned in a 2013 review, in light of several documented cases of humans surviving much higher doses; the 2013 review suggests that the lower limit resulting in fatal events is 500–1000 mg of ingested nicotine, which is equivalent to 6.5–13 mg/kg orally.[86] Reports of serious adverse effects associated with acute nicotine toxicity that resulting in hospitalization were very uncommon.[87] Death from intentional nicotine poisoning is very uncommon.[72] Clear labeling of devices and e-liquid could reduce unintentional exposures.[74] Child-proof packaging and directions for safe handling of e-liquids could minimize some of the risks.[81] In January 2016, the Child Nicotine Poisoning Prevention Act of 2015 was passed into law in the US,[88] which requires child-proof packaging.[89]

There was inconsistent labeling of the actual nicotine content on e-liquid cartridges from some brands,[5] and some nicotine has been found in ‘no nicotine' liquids.[21] A 2015 PHE report noted overall the labelling accuracy has improved.[90] Most inaccurately-labelled examples contained less nicotine than stated.[90] Due to nicotine content inconstancy, it is recommended that e-cigarette companies develop quality standards with respect to nicotine content.[24]

Because of the lack of production standards and controls, the pureness of e-liquid are generally not dependable, and testing of some products has shown the existence of harmful substances.[81] The German Cancer Research Center in Germany released a report stating that e-cigarettes cannot be considered safe, in part due to technical flaws that have been found.[38] This includes leaking cartridges, accidental contact with nicotine when changing cartridges, and potential of unintended overdose.[38] The Therapeutic Goods Administration (TGA) of Australia has stated that, "Some overseas studies suggest that electronic cigarettes containing nicotine may be dangerous, delivering unreliable doses of nicotine (above or below the stated quantity), or containing toxic chemicals or carcinogens, or leaking nicotine. Leaked nicotine is a poisoning hazard for the user of electronic cigarettes, as well as others around them, particularly children."[91]

Cannabinoid-containing e-liquids need lengthy, complex processing, some being available online without any toxicological and clinical evaluation.[92] It is thought that cannabinoids vaped at reduced temperatures is safer because it creates smaller amounts of toxicants than the burning of a hot cannabis cigarette.[92] The health effects of vaping cannabis formulations is mostly unknown.[92]

Most e-cigarettes use lithium batteries, the improper use of which may result in accidents.[9] It has been recommended that manufacturing quality standards be imposed in order to prevent such accidents.[9] Better product design and standards could probably reduce some of the risks.[79] Concern exists from risks associated with e-cigarette explosions for children and adults.[18]

Some batteries are not well designed, are made with poor quality components, or have defects.[1] Major injuries have occurred from battery explosions and fires.[5] A man endured a unilateral corneoscleral laceration with prolapsed iris tissue and hyphemato to the eye area when an e-cigarette exploded in his mouth.[93] A young man endured bilateral corneal burns to the eye area when an e-cigarette exploded near his chest.[93] E-cigarette explosions have resulted in burns, lost teeth, neck fractures, and battery acid contact to the face, mouth, and eyes.[93] A man died when charging an e-cigarette blown up and caught on fire next to oxygen equipment.[93] House and car fires and skin burns have resulted from some of the explosions.[1] The explosions were the result of extended charging, use of unsuitable chargers, or design flaws.[9] There is a possible risk to bystanders from e-cigarette explosions.[93] There is also a risk of property damage as a result of flammable materials catching on fire from an e-cigarette explosion.[93] The United States Fire Administration said that 25 fires and explosions were caused by e-cigarettes between 2009 and August 2014.[94] In the UK fire service call-outs had risen, from 43 in 2013 to 62 in 2014.[95] A 2015 PHE report concluded that the risks of fire from e-cigarettes "appear to be comparable to similar electrical goods".[96] Since e-cigarettes are not subjected to product safety testing, they may not have safety designs to avoid overheating, thermal runaway, and battery failure including fire and explosions.[93] There is inadequate product labeling to inform users of the possible serious harms.[93] The risk from serious adverse effects is low, but the aftermath may be disastrous in respect to an e-cigarette blast.[93] Victims have filed lawsuits to make restitution from the e-cigarette blasts.[41] Adverse effects may be under-reported because reports to the FDA is voluntary.[93]

In January 2015 the US Federal Aviation Administration issued a safety alert to air carriers that e-cigarettes should not be allowed in checked baggage after a review of fire safety issues, including two fires caused by e-cigarettes in checked baggage.[94][97] The International Civil Aviation Organization, a United Nations agency, also recommends prohibiting e-cigarettes in checked luggage.[94] A spokesman for the Tobacco Vapor Electronic Cigarette Association said that e-cigarettes do not pose a problem if they are packed correctly in static-free packaging, but that irresponsible people may sometimes pack them carelessly or tamper with them.[94] In-flight use of e-cigarettes is prohibited in the US.[97]

Users may alter many of the devices, such as using them to administer other drugs like cannabis.[5] E-liquid mixing is another way users tamper with e-cigarettes.[98] Mixing liquid in an unclean area runs the risk of contamination.[16] Users may add various flavorings and diluents.[98] Vodka or other forms of alcohol may also be added.[98] The addition of alcohol or nicotine could expose the user to more toxicants, especially when added in combinations.[98] Some ingredients in e-liquids could be flammable; this risk is more of concern for users who are inexperienced or do not use protective gear.[98] Users can adjust the voltage of some e-cigarettes.[98] The amount of vapor produced is controlled by the power of the battery, which has led some users to adjust their e-cigarettes to increase battery power to obtain a stronger nicotine "hit", but there is a small risk of battery explosion.[19] Some users add more or larger batteries to nonadjustable e-cigarettes, which may lead to battery leakage or explosion.[98] The extent to which teens are altering e-cigarettes, such as dripping the liquids onto the atomizer to get more nicotine intake, is not known.[18]

The long-term health impacts of e-cigarette use are unknown.[13] The long-term health impacts of the main chemicals nicotine and propylene glycol in the aerosol are not fully understood.[99] There is limited peer-reviewed data about the toxicity of e-cigarettes for a complete toxicological evaluation,[100] and their cytotoxicity is unknown.[15] The chemicals and toxicants included in e-cigarettes have not been completely disclosed and their safety is not guaranteed.[34] They are similar in toxicity to other nicotine replacement products,[101] but e-cigarettes manufacturing standards are variable standards, and many as a result are probably more toxic than nicotine replacement products.[102] The UK National Health Service noted that the toxic chemicals found by the FDA were at levels one-thousandth that of cigarette smoke, and that while there is no certainty that these small traces are harmless, initial test results are reassuring.[103] While there is variability in the ingredients and concentrations of ingredients in e-cigarette liquids, tobacco smoke contains thousands of chemicals, most of which are not understood and many of which are known to be harmful.[36]

Concerns about the carcinogenicity of e-cigarettes arise from both nicotine[28] and from other chemicals that may be in the vapor.[24] As regards nicotine, there is evidence from in vitro and animal research that nicotine may have a role as a tumor promoter, but carcinogenicity has not been demonstrated in vivo.[28] A 2014 Surgeon General of the United States report stated that the single relevant randomized trial "does not indicate a strong role for nicotine in promoting carcinogenesis in humans".[29] They concluded that "There is insufficient data to conclude that nicotine causes or contributes to cancer in humans, but there is evidence showing possible oral, esophageal, or pancreatic cancer risks".[29] Nicotine in the form of nicotine replacement products is less of a risk than compared to smoking,[29] and they have not been shown to be associated with cancer in the real world.[28]

There is no long-term research concerning the cancer risk related to the potentially small level of exposure to the identified carcinogens in the vapor.[8] In May 2014, Cancer Research UK stated that there are "very preliminary unpublished results that suggest that e-cigarettes promote tumour growth in human cells."[99] The e-cigarette vapors triggered DNA strand breaks and lowered cell survival in vitro.[41] A 2013 study found some samples of e-cigarette vapors had cytotoxic effects on cardiac muscle cells, though the effects were less than with cigarette smoke.[10] In October 2012, the World Medical Association stated, "Manufacturers and marketers of e-cigarettes often claim that use of their products is a safe alternative to smoking, particularly since they do not produce carcinogenic smoke. However, no studies have been conducted to determine that the vapor is not carcinogenic, and there are other potential risks associated with these devices."[104]

Chart showing various toxicants as measured in cigarette smoke and e-cigarette aerosol.[105]

Since nicotine-containing e-liquids are made from tobacco they may contain impurities like cotinine, anabasine, anatabine, myosmine and beta-nicotyrine.[13] The majority of e-cigarettes evaluated included carcinogenic tobacco-specific nitrosamines (TSNAs); heavy metals such as cadmium, nickel, and lead; and the carcinogen toluene.[34] However, in comparison to traditional cigarette smoke, the toxic substance levels identified in e-cigarette vapor were 9- to 450-fold less.[34] E-liquid with tin was cytotoxic.[12] E-cigarettes cannot be considered absolutely safe because there is no safe level for carcinogens.[106]

A 2014 review found higher levels of carcinogens and toxicants than in an FDA-approved nicotine inhaler, suggesting that FDA-approved devices may deliver nicotine more safely.[8] In 2014, The World Lung Foundation stated that "Researchers find that many e-cigarettes contain toxins, contaminants and carcinogens that conflict with the industry’s portrayal of its products as purer, healthier alternatives. They also find considerable variations in the amount of nicotine delivered by different brands. None of this information is made available to consumers so they really don’t know what they are ingesting, or how much."[107]

A 2014 review found "Various chemical substances and ultrafine particles known to be toxic, carcinogenic and/or to cause respiratory and heart distress have been identified in e-cigarette aerosols, cartridges, refill liquids and environmental emissions."[24] Few of the methods used to analyze the chemistry of e-cigarettes in the studies the review evaluated were validated.[24]

The propylene glycol molecule.

The primary base ingredients of the liquid solution is propylene glycol and glycerin.[5] About 20% to 27% of propylene glycol and glycerin-based liquid particles are inhaled.[108] The long-term effects of inhaled propylene glycol has not been studied,[58] and is unknown.[109] The effects of inhaled glycerin are unknown.[84] Being exposed to propylene glycol may cause irritation to the eyes and respiratory tract.[5] The risk from the inhalation of propylene glycol and glycerin is probably low.[13] Propylene glycol and glycerin have not been shown to be safe.[84] Some research states that propylene glycol emissions may cause respiratory irritation and raise the likelihood to develop asthma.[52] Long-term inhalation of propylene glycol indoors could increase risk to children to develop asthma.[38] To lessen the risks, most e-cigarettes companies began to use water and glycerin as replacement for propylene glycol.[52] The inhaled glycerin could cause lipoid pneumonia.[16]

Some e-cigarette products had acrolein identified in the aerosol.[13] It may be generated when glycerin is heated to higher temperatures.[13] Acrolein may induce irritation to the upper respiratory tract.[5] Acrolein levels were reduced by 60% in dual users and 80% for those that completely switched to e-cigarettes when compared to traditional cigarettes.[13] E-cigarettes vapor have been found to create oxidants and reactive oxygen species (OX/ROS).[19] OX/ROS could react with other substances in the vapor because they are highly reactive.[19] Although e-cigarettes have been found to contain OX/ROS at about 100 times less than in cigarette smoke, they probably induce meaningful biological effects.[19]

The toxicity of e-cigarettes and e-liquid can vary greatly, as there are differences in construction and materials in the delivery device, kind and origin of ingredients in the e-liquid, and the use or non-use of good manufacturing practices and quality control approaches.[100] If exposure of aerosols to propylene glycol and glycerin rises to levels that one would consider the exposure in association with a workplace setting, it would be sensible to investigate the health of exposed persons.[33] The short-term toxicity of e-cigarette use appears to be low, with the exception for some people with reactive airways.[21]

The essential propylene glycol and/or glycerin mixture may consist of natural or artificial substances to provide it flavor.[21] The cytotoxicity of e-liquids varies,[20] and contamination with various chemicals have been detected in the liquid.[21] Some liquids were very toxic and others had little or no cytotoxicity.[20] The cytotoxicity is mostly due to the amount and number of flavors added.[20] Since nicotine has a bitter taste, nicotine e-liquids contain chemicals to cover up the nicotine taste.[19] The liquids contain aromatic substances like tobacco, fruit, vanilla, caramel and coffee.[21] Generally, these additives are imprecisely described, using terms such as "vegetable flavoring".[21] Although they are approved for human consumption there are no studies on the short-term or long-term effects of inhaling them.[21] The safety of inhaling flavors is mostly unknown,[110] and their safety has not been determined by the Flavor and Extract Manufacturers Association.[41] In some cases e-liquids contain very large amounts of flavorings, which may cause irritation and inflammation on respiratory and cardiovascular systems.[69] Some flavors are regarded as toxic and a number of them resemble known carcinogens.[21] Some artificial flavors are known to be cytotoxic.[21] Unflavored vapor is less cytotoxic than flavored vapor.[23] A 2012 study demonstrated that in embryonic and adult cellular models, some substances of the vapor such as flavoring not found in tobacco smoke were cytotoxic.[111]

Cinnamaldehyde has been described as a highly cytotoxic material in vitro in cinnamon-flavored refill liquids.[1] Cinnamaldehyde have been identified as cytotoxic at the amount of about 400 times less than those allowed for use by the US Environmental Protection Agency.[9] Some e-liquids containing cinnamaldehyde stimulate TRPA1, which might induce effects on the lung.[19] E-liquids contain possibly toxic aldehydes and reactive oxygen species (ROS).[19] Many flavors are known aldehydes, such as anisaldehyde, cinnamaldehyde, and isovaleraldehyde.[19] The effects of aldehyde-containing flavors on pulmonary surfaces are unknown.[19] A 2012 study found butterscotch flavor was highly toxic with one liquid and two others had a low toxicity.[40] A 2014 in vitro study demonstrated that e-cigarette use of a "balsamic" flavor with no nicotine can activate the release of proinflammatory cytokine in lung epithelial cells and keratinocytes.[34] Some additives may be added to reduce the irritation on the pharynx.[84] The long-term toxicity is subject to the additives and contaminants in the e-liquid.[21]

Certain flavorings contain diacetyl and acetyl propionyl which give a buttery taste.[31] Diacetyl and acetyl propionyl are associated with bronchiolitis obliterans.[31] A 2015 review recommended for specific regulation of diacetyl and acetyl propionyl in e-liquid, which are safe when ingested but have been associated with respiratory harm when inhaled.[6] Both diacetyl and acetyl-propionyl have been found in concentrations above those recommended by the US National Institute for Occupational Safety and Health.[31] Diacetyl is normally found at lower levels in e-cigarettes than in traditional cigarettes.[31] Concerns exist that the flavors and additives in e-cigarettes might lead to diseases, including the popcorn lung.[112] The cardiovascular effects, including a vast range of flavorings and fragrances, is unknown.[113] The irritants butyl acetate, diethyl carbonate, benzoic acid, quinoline, bis(2-ethylhexyl) phthalate, and 2,6-dimethyl phenol were present as undeclared ingredients in the e-liquid.[62] The precise ingredients of e-cigarettes are not known.[114]

The IARC has categorized formaldehyde as a human carcinogen, and acetaldehyde is categorized as a potential carcinogenic to humans.[22] Aldehydes may cause harmful health effects; though, in the majority of cases, the amounts inhaled are less than with traditional cigarettes.[22] Many chemical compounds can inadvertently be produced from e-cigarettes, especially carbonyl compounds like formaldehyde, acetaldehyde, acrolein, and glyoxal by the chemical reaction of the e-liquid when the nichrome wire (heating element) is heated,[22] to high temperatures.[34] These compounds are frequently identified in e-cigarette aerosols.[22] The propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette aerosols.[22] The levels of toxic chemicals in the vapor were found to be 1 to 2 orders of magnitude smaller than with cigarette smoke but greater than from a nicotine inhaler.[5] Nearly all e-cigarettes evaluated, toxic and irritation-causing carbonyls were identified.[34] Reports regarding the levels of toxic chemicals were inconsistent.[34] This includes a study showing that the levels of toxicants in e-cigarettes may be higher than with cigarette smoke.[34]

Battery output voltage influences the level of the carbonyl substances in the vapor.[22] A few new e-cigarettes let users boost the amount of vapor and nicotine provided by modifying the battery output voltage.[22] E-cigarettes with higher voltages (5.0 V[20]) can emit carcinogens including formaldehyde at levels comparable to cigarette smoke,[115] while reduced voltages (3.0 V[24]) generate aerosol with levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than in cigarette smoke.[22] "Dripping", where the liquid is dripped directly onto the atomizer, can create carbonyls including formaldehyde.[116]

A 2015 PHE report found that normal e-cigarette use generates very low levels of aldehydes.[26] Normal usage of e-cigarettes generates very low levels of formaldehyde,[23] and at normal settings they generate very low levels of formaldehyde.[26] Later-generation e-cigarettes used with higher power may generate equal or higher levels of formaldehyde than compared to smoking.[14][Notes 2] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[25] A 2015 PHE report found that by applying maximum power and increasing the time the device is used on a puffing machine, e-liquids can thermally degrade and produce high levels of formaldehyde.[26] Users detect the "dry puff" and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[27] However, e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[19]

Possible side effects of nicotine.[117] A 2015 comparative risk analysis of drugs found the nicotine's margin of exposure (MOE) values were in a lower risk range than cocaine, heroine, and alcohol, whereas its MOE values was in a higher risk range than MDMA, methamphetamine, and methadone.[118] Shown above is the MOE for daily drug use from the analysis.[118]

Pregnant women, breastfeeding mothers, and the elderly are more sensitive to nicotine than other individuals.[110] There are safety issues with the nicotine exposure from e-cigarettes, which may cause addiction and other adverse effects.[24] Nicotine is regarded as a potentially lethal poison.[17] Concerns exist that vaping can be harmful by exposing users to toxic levels of nicotine.[17] At low amounts, it has a mild analgesic effect.[110] At high enough doses, nicotine may result in nausea, vomiting, diarrhea, salivation, bradyarrhythmia, and possibly seizures and hypoventilation.[35] However, at the low amount of nicotine provided by e-cigarettes fatal overdose from use is unlikely; in contrast, the potent amount of nicotine in e-cigarettes liquids may be toxic if it is accidentally ingested or absorbed via the skin.[17] The health effects of nicotine in infants and children are unclear.[35]

E-cigarettes provide nicotine to the blood quicker than nicotine inhalers.[53] The levels were above that of nicotine replacement product users.[17] E-cigarettes seem to have a pharmacokinetic nicotine profile closer to nicotine replacement products than with traditional cigarettes.[119] How efficiently different e-cigarettes give nicotine is unclear.[17]Serum cotinine levels are comparable to that of traditional cigarettes,[120] but are inharmonious and rely upon the user and the device.[8] Blood nicotine levels raised more gradually and took more time to get to peak concentration with e-cigarettes than with traditional cigarettes.[121]

When compared to traditional cigarettes older devices usually delivered low amounts of nicotine.[17] E-cigarette use can be associated with a substantial dispersion of nicotine, thus generating a plasma nicotine concentration which can be comparable to that of traditional cigarettes.[122] This is due to the minute nicotine particles in the vapor, which permit quick delivery into the bloodstream.[122] The nicotine delivered from e-cigarettes enters the body slower than traditional cigarettes.[123] Studies suggest that inexperienced users obtain moderate amounts of nicotine from e-cigarettes.[124] Concerns were raised over inconsistent amounts of nicotine delivered when drawing on the device.[125]

Later-generation e-cigarettes gives nicotine more effectively than first-generation e-cigarettes.[1] Later-generation models with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[17] E-cigarettes with stronger batteries heat solutions to higher temperatures, which may raise blood nicotine levels to those of traditional cigarettes.[40] Research suggests that experienced e-cigarettes users are able to get as much nicotine from e-cigarettes as traditional cigarettes.[17] Later-generation e-cigarettes containing sufficient nicotine elevates heart rate comparable to traditional cigarettes.[113]

The health effects of long-term nicotine use is unknown.[109] It may be decades before the long-term health effects of nicotine vapor inhalation is known.[126] It is not recommended for non-smokers.[9] Nicotine affects practically every cell in the body.[110] Nicotine can cause high blood pressure and abnormal heart rhythms.[107] Vapers that get a higher amount of blood nicotine are probably correlated with increased heart rates.[87] Nicotine may have adverse effects on lipids,[127] cause insulin resistance.[40] and can lower coronary blood flow.[113] Nicotine lowers estrogen levels and has been associated with early menopause in women.[107] Nicotine could have cancer-promoting properties, therefore long-term use may not be harmless.[98] Nicotine may result in neuroplasticity variations in the brain.[80] Nicotine could make cancer therapies less effective.[16]

Children are more sensitive to nicotine than adults.[110] In youth, nicotine may affect capabilities connected with higher cognitive function processes,[35] later achievement, as well as the chance of nicotine addiction for life.[107] The adolescents developing brain is especially sensitive to the harmful effects of nicotine.[82] A short period of regular or occasional nicotine exposure in adolescence exerts long-term neurobehavioral damage.[82] In August 2014, the American Heart Association noted that "e-cigarettes could fuel and promote nicotine addiction, especially in children."[40] A policy statement by the UK's Faculty of Public Health has stated, "A key concern for everyone in public health is that children and young people are being targeted by mass advertising of e-cigarettes. There is a danger that e-cigarettes will lead to young people and non-smokers becoming addicted to nicotine and smoking. Evidence from the US backs up this concern."[128]

There is limited evidence on the long-term exposure of metals.[9] Exposure to the levels and kinds of metals found in the aerosol relies upon the material and other manufacturing designs of the heating element.[40] E-cigarettes contain some contamination with small amounts of metals in the emissions but it is not likely that these amounts would cause a serious risk to the health of the user.[9] The device itself could contribute to the toxicity from the tiny amounts of silicate and heavy metals found in the liquid and vapor,[116] because they have metal parts that come in contact with the e-liquid.[9] Low levels of possibly harmful chromium, lead, and nickel metals have been found in the emissions.[40] Chromium and nickel nanoparticles have also been found.[5]

Metals may adversely affect the nervous system.[70] A 2013 review found metallic and nanoparticles are associated with respiratory distress and disease.[129] A 2014 review found considerable amounts of tin, metals, and silicate particles that came from various components of the e-cigarette were released into the aerosol, which result in exposure that could be higher than with cigarette smoke.[34] A 2013 study found metal particles in the aerosol were at levels 10-50 times less than permitted in inhalation medicines.[13] A 2014 review suggested that there is no evidence of contamination of the aerosol with metals that justifies a health concern.[33]

The risks to the lungs are not fully understood,[19] and concern exists regarding the negative effects on lung function.[130] There is limited evidence on the long-term health effects to the lungs.[14] Many ingredients used in e-liquids have not been examined in the lung.[19] The effects of e-cigarette use in respect to asthma and other respiratory diseases are unknown.[13] A 2015 review found e-cigarettes may induce acute lung disease.[14] A 2015 study found that e-cigarette vapors can induce oxidative stress in lung endothelial cells.[69] Constant lung inflammation as a result of the vapor could result in lung pathogenesis and induce serious diseases, including chronic obstructive pulmonary disease and fibrosis.[41] The limited evidence suggests that e-cigarettes produce less short-term effects on lung function than traditional cigarettes.[8] A 2014 case report observed the correlation between sub-acute bronchiolitis and vaping.[14] After quitting vaping the symptoms improved.[14]

The long-term effects regarding respiratory flow resistance are unknown.[60] E-cigarettes could harm the respiratory system.[21] The immediate effects of e-cigarettes after 5 minutes of use on pulmonary function resulted in considerable increases in resistance to lung airflow.[1] A 2013 review found an instant increase in airway resistance after using a single e-cigarette.[21] Any reported harmful effects to cardiovascular and respiratory functions after short-term use of e-cigarettes were appreciably milder in comparison to cigarette smoke.[9] When used in the short-term, an e-cigarette resulted in a rise of respiratory resistance comparatively to traditional cigarettes.[60] E-cigarette use could result in respiratory diseases among youth.[131]

There is no data available on the long-term cardiovascular effects.[8] There is no published research available on vaping and thrombosis, platelet reactivity, atherosclerosis, or blood vessel function.[14] The minute nicotine particles in the vapor could increase the risk of cardiac arrhythmias and hypertension which may put some users, particularly those with atherosclerosis or other cardiovascular risk factors, at significant risk of acute coronary syndrome.[122] Some case reports documented the possible cardiovascular adverse effects from using e-cigarettes, the majority associated was with improper use.[122] Even though e-cigarettes are anticipated to produce fewer harmful substances than traditional cigarettes, limited evidence supports they comparatively have a lessened raised cardiovascular risk.[122] E-cigarette use leads to sympathomimetic effects because of nicotine intake.[132] It is argued that there could be a risk for harmful effects, including tachycardia-induced cardiomyopathy.[132] E-cigarettes containing nicotine may have a lower cardiovascular effect than traditional cigarettes containing nicotine.[113] Short-term physiological effects include increases in blood pressure and heart rate.[14] A 2012 case report found a correlation between paroxysmal atrial fibrillation and vaping.[14]

Comparable to a traditional cigarette, e-cigarette particles are tiny enough to enter the alveoli, enabling nicotine absorption.[1] These particles are also tiny enough to go deep in the lungs and enter into the systemic circulation.[5] Local pulmonary toxicity may occur because metal nanoparticles can deposit in the lung's alveolar sacs.[5] E-cigarettes companies assert that the particulates produced by an e-cigarette are too tiny to be deposited in the alveoli.[53] Different devices generate different particle sizes and cause different depositions in the respiratory tract, even from the same nicotine liquid.[115] The aerosol production of e-cigarettes during vaping decreases, which requires a more forceful suction to create a similar volume of aerosol.[66] A more forceful suction could affect the deposition of substances into the lungs.[66] Reports in the literature have shown respiratory and cardiovascular effects by these smaller size particles, suggesting a possible health concern.[133]

Concern exists regarding the immunological effects of e-liquid, and analysis on animals demonstrate that e-liquid vapor, appear to have adverse effects on the immune system.[87] There were reports of e-cigarettes causing an immune system reaction involving inflammation of the gastrointestinal system.[41] Long-term use could increase the risk of tuberculosis.[12] It is possible that e-cigarettes could harm the periodontium because of the effects of nicotine on gum tissues and the immune system.[134] Some health effects associated with e-cigarette use can include recurring ulcerative colitis, lipoid pneumonia, acute eosinophilic pneumonitis, sub-acute bronchial toxicity, reversible cerebral vasoconstriction syndrome, and reversal of chronic idiopathic neutrophilia.[87]

Aerosol (vapor) exhaled by an e-cigarette user.

The aerosol of e-cigarettes is generated when the e-liquid reaches a temperature of roughly 100-250 °C within a chamber.[19] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[24] In physics, a vapor is a substance in the gas phase whereas an aerosol is a suspension of tiny particles of liquid, solid or both within a gas.[24] The aerosol is made-up of liquid sub-micron particles of condensed vapor,[135] which mostly consist of propylene glycol, glycerol, water, flavorings, nicotine, and other chemicals.[9] After a puff, inhalation of the aerosol travels from the device into the mouth and lungs.[24] The particle size distribution and sum of particles emitted by e-cigarettes are like traditional cigarettes, with the majority of particles in the ultrafine range.[5]

Various bottles of e-liquid.

After the aerosol is inhaled, it is exhaled.[24] Emissions from electronic cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different[9] The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled vapor.[21] Bystanders are exposed to these particles from exhaled e-cigarette vapor.[5] There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors, and have significant adverse effects.[34][129] Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted.[123] Thus, cardiocirculatory effects caused by carbon monoxide are not likely.[123] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[35] E-cigarettes pose many safety concerns to children.[35] For example, indoor surfaces can accumulate nicotine where e-cigarettes were used, which may be inhaled by children, particularly youngsters, long after they were used.[35]

E-liquid is the mixture used in vapor products such as electronic cigarettes.[52] The main ingredients in the e-liquid usually are propylene glycol, glycerin, nicotine, and flavorings.[101] However, there are e-liquids sold without propylene glycol, nicotine, or flavors.[17][52][61] The liquid typically contains 95% propylene glycol and glycerin.[84] The flavorings may be natural or artificial.[21] About 8,000 flavors exist as of 2014.[136] There are many e-liquids manufacturers in the USA and worldwide.[137] While there are currently no US Food and Drug Administration (FDA) manufacturing standards for e-liquid, the FDA has proposed regulations that are expected to be finalized in late 2015.[138] Industry standards have been created and published by the American E-liquid Manufacturing Standards Association (AEMSA).[139]

Concerns exists regarding pregnant women exposure to e-cigarette vapor through direct use or via exhaled vapor.[5] No evidence have shown that e-cigarettes are safe to use for pregnant women.[140] No amount of nicotine is safe for pregnant women.[140] As of 2014[update], there are no conclusions on the possible hazards of pregnant women using e-cigarettes, and there is a developing research on the negative effects of nicotine on prenatal brain development.[8] E-cigarette are assumed to be dangerous to the fetus during pregnancy if e-cigarettes are used by the mother.[141] Nicotine is harmful to the growing fetus.[142] Nicotine accumulates in the fetus because it goes through the placenta.[38]

As of 2015[update], the long-term issues of e-cigarettes on both mother and unborn baby are unknown.[143] Prenatal nicotine exposure is associated with adverse effects on the growing fetus, including effects to normal growth of the endocrine, reproductive, respiratory, cardiovascular, and neurologic systems.[140] Prenatal nicotine exposure is associated with lower birth weights than other babies,[140]stillbirth,[82]sudden infant death syndrome, and alterations to normal brain development.[140] Prenatal nicotine exposure is associated with asthma and wheezing which may continue into adulthood.[140]Gestational age nicotine exposure is associated with many neurological deficits.[140] Prenatal exposure has been associated with obesity, diabetes, high cholesterol and high blood pressure in minors.[107] Prenatal nicotine exposure in females may lead toward early menarche.[140] An infant was born with necrotizing enterocolitis due to e-cigarette use during pregnancy.[41]

In what way the e-liquid ingredients could affect a fetus is unknown.[2] The toxicity of e-liquid flavorings was higher in embryonic stem cells compared to differentiated adult pulmonary fibroblasts, leading to concerns about pregnant women being exposed to the second-hand vapor.[109] There are concerns about the health impacts of pediatric exposure to second-hand and third-hand e-cigarette vapor.[18] The Surgeon General's 2014 report found "that nicotine adversely affects maternal and fetal health during pregnancy, and that exposure to nicotine during fetal development has lasting adverse consequences for brain development."[17] The belief that e-cigarettes are safer than traditional cigarettes could increase their use in pregnant women.[1] The toxic effects identified with e-cigarette refill liquids on stem cells may be interpreted as embryonic death or birth defects.[1] Since e-cigarettes are not validated as cessation tools, may contain nicotine at inconsistent levels and added ingredients that are possibly harmful, allowing e-cigarettes to be used among pregnant women to decrease smoking puts this group at considerable risk.[35] There is concern for breastfeeding women using e-cigarettes, due to the lack of data on propylene glycol transferring to breastmilk.[21]

There is limited information available on any environmental issues connected to the production, usage, and disposal of e-cigarette models that use cartridges.[37] As of 2014[update], no formal studies have been done to evaluate the environmental effects of making or disposing of any part of e-cigarettes including the batteries or nicotine production.[37] As of 2014[update], it is uncertain if the nicotine in e-liquid is United States Pharmacopeia-grade nicotine, a tobacco extract, or synthetic nicotine when questioning the environmental impact of how it is made.[37] It is not clear which manufacturing methods are used to make the nicotine used in e-cigarettes.[37] The emissions from making nicotine could be considerable from manufacturing if not appropriately controlled.[37] Some e-cigarette brands that use cartridges state their products are ‘eco-friendly’ or ‘green’, despite the absence of any supporting studies.[37] Some writers contend that such marketing may raise sales and increase e-cigarette interest, particularly among minors.[37]

It is unclear how many traditional cigarettes are comparable to using one e-cigarette that uses a cartridge for the average user.[37] Information is limited on energy and materials used for production of e-cigarettes versus traditional cigarettes, for comparable use.[37] E-cigarettes can be made manually put together in small factories, or they can be made in automated lines on a much bigger scale.[37] Larger plants will produce greater emissions to the surrounding environment, and thus will have a greater environmental impact.[37] Although some brands have begun recycling services for their e-cigarette cartridges and batteries, the prevalence of recycling is unknown, as is the prevalence of information provided by manufacturers on how to recycle disposable parts.[37] A 2014 review found "disposable e-cigarettes might cause an electrical waste problem."[123] Since the majority of e-cigarettes are reusable they are possibly more environmentally friendly than using single-use devices.[144] Compared to traditional cigarettes, e-cigarettes do not create litter in the form of discarded cigarette butts.[144] Traditional cigarette tend to end up in the ocean where they cause pollution.[144]

Marketing and advertisement affects the public’s perception of e-cigarettes.[109] Some tobacco users think vaping is safer than tobacco or other smoking cessation aids.[145] It is generally considered by users that e-cigarettes are safer than tobacco.[114] Many users think that e-cigarettes are healthier than traditional cigarettes for personal use or for other people.[58] Usually, only a small proportion of users are concerned about the possible adverse health effects or toxicity of e-cigarettes.[58] A 2014 worldwide survey found that 88% of respondents stated that vaping were less harmful than cigarette smoke and 11% believed that vaping were absolutely harmless.[146] A 2013 four-country survey found higher than 75% of current and former smokers think e-cigarettes are safer than traditional cigarettes.[1] The UK Action on Smoking and Health (ASH) found that in 2015, compared to the year before, "there has been a growing false belief that electronic cigarettes could be as harmful as smoking".[147] Among smokers who had heard of e-cigarettes but never tried them, this "perception of harm has nearly doubled from 12% in 2014 to 22% in 2015."[147] The UK ASH expressed concern that "The growth of this false perception risks discouraging many smokers from using electronic cigarettes to quit and keep them smoking instead which would be bad for their health and the health of those around them."[147]

A 2015 PHE report noted that in the US belief among respondents to a survey that vaping was safer than smoking cigarettes fell from 82% in 2010 to 51% in 2014.[148] The report blamed "misinterpreted research findings", attracting negative media coverage, for the growth in the "inaccurate" belief that e-cigarettes were as harmful as smoking,and concluded that "There is a need to publicise the current best estimate that using EC is around 95% safer than smoking".[duplication?][149]

^Tomashefski, Amy (2016). "The perceived effects of electronic cigarettes on health by adult users: A state of the science systematic literature review". Journal of the American Association of Nurse Practitioners: n/a–n/a. doi:10.1002/2327-6924.12358. ISSN 2327-6886. PMID 26997487.

^ abc"Electronic cigarette use among smokers slows as perceptions of harm increase". ASH. 22 May 2015. Retrieved 6 August 2015.

UK

(Redirected from Health effects of electronic cigarettes)

The safetyofelectronic cigarettes is uncertain.[1][2][3] There is little data about their safety, and considerable variability among e-cigarettes and in their liquid ingredients[4] and thus the contents of the aerosol delivered to the user.[5] Reviews on the safety of e-cigarettes have reached significantly different conclusions.[6] A 2014 World Health Organization (WHO) report cautioned about potential risks of using e-cigarettes.[7] Regulated US Food and Drug Administration (FDA) products such as nicotine inhalers are likely safer than e-cigarettes,.[8] A systematic review suggests that e-cigarettes are less harmful than smoking and since they contain no tobacco and do not involve combustion, users may avoid several harmful constituents usually found in tobacco smoke.[9][10][11] However, e-cigarettes cannot be considered harmless.[12]

E-cigarettes have been found to reduce lung and myocardial function, increase inflammation, and have toxic content including carcinogens, but to a much lower extent than combustible cigarettes in virtually all cases.[3][13] The long-term effects of e-cigarette use are unknown.[13][14][15] A 2015 study found serious adverse events related to e-cigarettes were hypotension, seizure, chest pain, rapid heartbeat, disorientation, and congestive heart failure but it was unclear to the degree they were the result of e-cigarettes.[16] Less serious adverse effects may include abdominal pain, headache, blurry vision,[16] throat and mouth irritation, vomiting, nausea, and coughing.[5] A 2014 WHO report said, "ENDS [electronic nicotine delivery system] use poses serious threats to adolescents and fetuses."[7] Aside from toxicity exposure in normal use, there are also risks from misuse or accidents[9] such as nicotine poisoning (especially among infants and children),[17] contact with liquid nicotine,[18] fires caused by vaporizer malfunction,[5] and explosions resulting from extended charging, unsuitable chargers, or design flaws.[9] Battery explosions are caused by an increase in internal battery temperature and some have resulted in severe skin burns.[1] There is a small risk of battery explosion in devices modified to increase battery power.[19]

The cytotoxicity of e-liquids varies,[20] and contamination with various chemicals have been detected in the liquid.[21] Metal parts of e-cigarettes in contact with the e-liquid can contaminate it with metals.[9] Many chemicals including carbonyl compounds such as formaldehyde can inadvertently be produced when the nichrome wire (heating element) that touches the e-liquid is heated and chemically reacted with the liquid.[22] Normal usage of e-cigarettes,[23] and reduced voltage (3.0 V[24]) devices generate very low levels of formaldehyde.[22] Later-generation e-cigarettes used with higher power may generate equal or higher levels of formaldehyde than compared to smoking.[14][Notes 1] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[25] A 2015 Public Health England (PHE) report found that high levels of formaldehyde only occurred in overheated "dry-puffing".[26] Users detect the "dry puff" and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[27] However, e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[19] E-cigarette users who use devices that contain nicotine are exposed to its potentially harmful effects.[24] Nicotine is associated with cardiovascular disease, potential birth defects, and poisoning.[28]In vitro studies of nicotine have associated it with cancer, but carcinogenicity has not been demonstrated in vivo.[28] There is inadequate research to demonstrate that nicotine is associated with cancer in humans.[29] The risk is probably low from the inhalation of propylene glycol and glycerin.[13] No information is available on the long-term effects of the inhalation of flavors.[21]

E-cigarettes create an aerosol that consists of fine and ultrafine particles of particulate matter, with the majority of particles in the ultrafine range.[5][30] The vapor have been found to contain flavors, propylene glycol, glycerin, nicotine, tiny amounts of toxicants, carcinogens, heavy metals, and metal nanoparticles, and other substances.[5][13] Exactly what the vapor comprises varies in composition and concentration across and within manufacturers.[24] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[31] The majority of toxic chemicals found in tobacco smoke are absent in e-cigarette vapor.[9] E-cigarette vapor contains lower concentrations of potentially toxic chemicals than with cigarette smoke.[32] Those which are present, are mostly below 1% the corresponding levels permissible by workplace safety standards.[33] But workplace safety standards do not recognize exposure to certain vulnerable groups such as people with medical ailments, children, and infants who may be exposed to second-hand vapor.[5] Concern exists that some of the mainstream vapor exhaled by e-cigarette users may be inhaled by bystanders, particularly indoors.[34] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[35] A 2014 review recommended that e-cigarettes should be regulated for consumer safety.[36] There is limited information available on the environmental issues around production, use, and disposal of e-cigarettes that use cartridges.[37]

Reviews on the safety of e-cigarettes, evaluating roughly the same studies, have reached significantly different conclusions.[6] Due to various methodological issues, severe conflicts of interest, and inconsistent research, no definite conclusions can be determined regarding the safety of e-cigarettes.[12] However, e-cigarettes cannot be regarded as harmless.[12] There is little data about their safety, and considerable variability among vaporizers and in their liquid ingredients[4] and thus the contents of the aerosol delivered to the user.[5] The health community, pharmaceutical industry, and other groups have raised concerns about the emerging phenomenon of e-cigarettes, including the unknown health risks from long-term use of e-cigarettes.[36] Concern exists that the majority of smokers attempting to quit by vaping may stop smoking but maintain nicotine intake because their long-term effects are not clear.[38] A policy statement by the American Association for Cancer Research and the American Society of Clinical Oncology has reported that "The benefits and harms must be evaluated with respect to the population as a whole, taking into account the effect on youth, adults, nonsmokers, and smokers."[17] A July 2014 World Health Organization (WHO) report cautioned about the potential risks to children and adolescents, pregnant women, and women of reproductive age regarding e-cigarette use.[7]

It is recommended the precautionary principle be used for e-cigarettes because of the long history of the tobacco crisis, in order to assess their benefits and long-term effects and to avoid another nicotine crisis.[39] A 2014 review recommended that e-cigarettes could be adequately regulated for consumer safety with existing regulations on the design of electronic products.[36] Regulation of the production and promotion of e-cigarettes may help lower some adverse effects associated with tobacco use.[34] The entrance of large US tobacco manufacturers, which are Altria Group, Reynolds American, and Lorillard, into the e-cigarette sector raises many potential public health issues.[40] Instead of encouraging quitting, the tobacco industry could market e-cigarettes as a way to get around clean indoor air laws, which promotes dual use.[40] The industry could also lead vapers to tobacco products, which would increase instead of decrease overall addiction.[40]

The health effects related to e-cigarette use is mostly unknown.[41] The health effects on intensive e-cigarette users are unknown.[14] The effect on population health from e-cigarettes is unknown.[8] Smokefree.gov, a website run by the Tobacco Control Research Branch of the National Cancer Institute to provide information to help quit smoking, stated that "Since e-cigs aren’t regulated yet, there’s no way of knowing how much nicotine is in them or what other chemicals they contain. These two things make the safety of e-cigs unclear."[42] The English National Health Service has stated, "While e-cigarettes may be safer than conventional cigarettes, we don’t yet know the long-term effects of vaping on the body."[43] The American Diabetes Association states "There is no evidence that e-cigarettes are a healthier alternative to smoking."[44] In August 2014, the Forum of International Respiratory Societies stated that e-cigarettes have not been demonstrated to be safe.[45]Health Canada has stated that, "their safety, quality, and efficacy remain unknown."[46] The National Institute on Drug Abuse stated that "There are currently no accepted measures to confirm their purity or safety, and the long-term health consequence of e-cigarette use remain unknown."[47]

Effects of vaping, compared to tobacco smoking.[48]

A 2015 Public Health England (PHE) report stated that e-cigarettes are estimated to be 95% less harmful than smoking,[49] although this estimate has been disputed.[50] In June 2014, the Royal College of Physicians stated that, "On the basis of available evidence, the RCP believes that e-cigarettes could lead to significant falls in the prevalence of smoking in the UK, prevent many deaths and episodes of serious illness, and help to reduce the social inequalities in health that tobacco smoking currently exacerbates."[51] A 2014 systematic review suggests that e-cigarettes are less harmful than smoking because there is no tobacco, no combustion, and users may avoid several harmful constituents usually found in tobacco smoke.[9] A 2014 review found that e-cigarette aerosol contains far fewer carcinogens than tobacco smoke, and concluded that e-cigarettes "impart a lower potential disease burden" than traditional cigarettes.[52] Scientific studies advocate caution before designating e-cigarettes as beneficial but vapers continue to believe they are beneficial.[53]

The American Cancer Society has stated, "The makers of e-cigarettes say that the ingredients are "safe," but this only means the ingredients have been found to be safe to eat. Inhaling a substance is not the same as swallowing it. There are questions about how safe it is to inhale some substances in the e-cigarette vapor into the lungs."[54] The Canadian Cancer Society has stated that, "A few studies have shown that there may be low levels of harmful substances in some e-cigarettes, even if they don’t have nicotine."[55] In the UK a National Institute for Health and Care Excellence (NICE) guideline did not recommend e-cigarettes as there are questions regarding the safety, efficacy, and quality of these products.[56] The US National Association of County and City Health Officials has stated, "Public health experts have expressed concern that e-cigarettes may increase nicotine addiction and tobacco use in young people."[57] No long-term studies have evaluated future tobacco use as a result of e-cigarette use.[58] E-cigarette vapor potentially contains harmful substances not found in tobacco smoke.[31]

Possible adverse effects of vaping.[59]

As of 2015, the short-term and long-term effects from using e-cigarettes remain unclear.[14]Adverse effects are mostly associated with short-term use and the reported adverse effects decreased over time.[60] Long-term studies regarding the effects of constant use of e-cigarettes are unavailable.[60] The adverse effects of e-cigarettes on people with cancer is unknown.[17] A 2014 Cochrane review found no serious adverse effects reported in trials,[61] but serious events have been reported in case studies.[13]

The evidence suggests they produce less harmful effects than combusted tobacco.[11] The most frequently reported less harmful effects of vaping compared to smoking were reduced shortness of breath, reduced cough, reduced spitting, and reduced sore throat.[53] Many health benefits are associated with switching from tobacco to e-cigarettes including decreased weight gain after smoking cessation and improved exercise tolerance.[62] Vaping is possibly harmful by virtue of putting off quitting smoking, serving as a gateway to tobacco use in never-smokers or causing a return to smoking in former smokers.[63] Many people use e-cigarettes to quit smoking, but few succeed.[64] They frequently use both, which increases their health risks by using both products.[64] Quitting smoking entirely would probably have much greater beneficial effects to overall health than vaping to decrease the number of cigarettes smoked.[5]

More serious adverse effects frequently related with smoking cessation including depression, insomnia, and anxiety are uncommon with e-cigarette use.[16] A 2015 study found serious adverse events related to e-cigarettes were hypotension, seizure, chest pain, rapid heartbeat, disorientation, and congestive heart failure but it was unclear to the degree they were the result of e-cigarettes.[16] Less serious adverse effects include abdominal pain, headache, blurry vision,[16] throat and mouth irritation, vomiting, nausea, and coughing.[5] Short-term adverse effects reported most often were mouth and throat irritation, dry cough, and nausea.[60] The majority of adverse effects reported were nausea, vomiting, dizziness and oral irritation.[9] Some case reports found harms to health brought about by e-cigarettes in many countries, such as the US and in Europe; the most common effect was dryness of the mouth and throat.[22] Some e-cigarettes users experience adverse effects like throat irritation which could be the result of exposure to nicotine, nicotine solvents, or toxicants in the aerosol.[17]

The US Food and Drug Administration Center for Tobacco Products reported between 2008 and the beginning of 2012, 47 cases of adverse effects associated with e-cigarettes, of which eight were considered serious.[13] Two peer-reviewed reports of lipoid pneumonia were related to e-cigarette use, as well as two reports in the media in Spain and the UK.[41] The man from the UK reportedly died from severe lipoid pneumonia in 2011.[41] Reports to the Food and Drug Administration (FDA) for minor adverse effects identified with using e-cigarettes include headache, chest pain, nausea, and cough.[1] Major adverse effects reported to the FDA included hospitalizations for pneumonia, congestive heart failure, seizure, rapid heart rate, and burns.[1] However no direct relationship has been proven between these effects and e-cigarette use, and some of them may be due to existing health problems.[1] Many of the observed negative effects from e-cigarette use concerning the nervous system and the sensory system are probably related to nicotine overdose or withdrawal.[65] Since e-cigarettes are intended to be used repeatedly, they can conveniently be used for an extended period of time, which may contribute to increased adverse effects.[66] E-cigarettes were associated with fewer adverse effects than nicotine patches.[67]

Symptoms of nicotine poisoning related to e-cigarette calls to US poison control centers.[68]

Nicotine poisoning related to e-cigarettes include ingestion, inhalation, or absorption via the skin or eyes.[17] Accidental poisoning can result from using undiluted concentrated nicotine when mistakenly used as prepared e-liquids.[69] E-cigarettes involve accidental nicotine exposure in children.[18] Accidental exposures in pediatric patients include ingesting of e-liquids and inhaling of e-cigarette vapors.[18] Choking on e-cigarette components is a potential risk.[18] It is recommended that youth access to e-cigarettes be prohibited.[70]

Four adults died in the US and Europe, after intentionally ingesting liquid.[41] Two children, one in the US in 2014 and another in Israel in 2013, died after ingesting liquid nicotine.[71] Death from accidental nicotine poisoning is very uncommon.[72]

Calls to US poison control centers related to e-cigarette exposures involved inhalations, eye exposures, skin exposures, and ingestion, in both adults and young children.[73] Minor, moderate, and serious adverse effects involved adults and young children.[74] Minor effects correlated with e-cigarette liquid poisoning were tachycardia, tremor, chest pain and hypertension.[75] More serious effects were bradycardia, hypotension, nausea, respiratory paralysis, atrial fibrillation and dyspnea.[75] The exact correlation is not fully known between these effects and e-cigarettes.[75] 58% of e-cigarette calls to US poison control centers were related to children 5 years old or less.[74] E-cigarette calls had a greater chance to report an adverse effect and a greater chance to report a moderate or major adverse effect than traditional cigarette calls.[74] Most of the e-cigarette and traditional cigarette calls were a minor effect.[74] Severe outcomes were more than 2.5 times more frequent in children exposed to e-cigarettes and nicotine e-liquid than with traditional cigarettes.[76] E-cigarette sales were roughly equivalent to just 3.5% of traditional cigarette sales, but of the total number of e-cigarette and traditional cigarette calls to US poison control centers in December 2014, the reported e-cigarettes calls were 44%.[74]

Poison control center calls in the US related to e-cigarettes was one call per month in September 2010 to over 200 calls per month in February 2014.[77]

From September 1, 2010 to December 31, 2014, the most frequent adverse effects to e-cigarettes and e-liquid reported to US poison control centers were: Ingestion exposure resulted in vomiting, nausea, drowsy, tachycardia, or agitation;[74] inhalation/nasal exposure resulted in nausea, vomiting, dizziness, agitated, or headache;[74] ocular exposure resulted in eye irritation or pain, red eye or conjunctivitis, blurred vision, headache, or corneal abrasion;[74] multiple routes of exposure resulted in eye irritation or pain, vomiting, red eye or conjunctivitis, nausea, or cough;[74] and dermal exposure that resulted in nausea, dizziness, vomiting, headache, or tachycardia.[74] The ten most frequent adverse effects to e-cigarettes and e-liquid reported to US poison control centers were vomiting (40.4%), eye irritation or pain (20.3%), nausea (16.8%), red eye or conjunctivitis (10.5%), dizziness (7.5%), tachycardia (7.1%), drowsiness (7.1%), agitation (6.3%), headache (4.8%), and cough (4.5%).[74] In nine reported calls, exposed individuals stated the device leaked.[74] In five reported calls, individuals used e-liquid for their eyes rather than use eye drops.[74] In one reported call, an infant was given the e-liquid by an adult who thought it was the infant's medication.[74] There were also reports of choking on e-cigarette components.[18]

From January 1, 2016 and April 30, 2016, the American Association of Poison Control Centers (AAPCC) reported 623 exposures related to e-cigarettes.[64] The AAPCC reported 3,067 exposures relating to e-cigarettes and liquid nicotine in 2015, and 3,783 in 2014.[78] From September 1, 2010 to December 31, 2014, there were at least 5,970 e-cigarette calls to US poison control centers.[74] Calls to US poison control centers related to e-cigarettes increased between September 2010 to February 2014, and of the total number of cigarettes and e-cigarettes calls, e-cigarette calls increased from 0.3% to 41.7%.[67] Calls to US poison controls centers related to e-cigarette liquid poisoning increased from 1 in September 2010 to 215 for the month of February 2014.[75] E-cigarette calls was 401 for the month of April 2014.[74] The California Poison Control System reported 35 cases of e-cigarette contact from 2010 to 2012, 14 were in children and 25 were from accidental contact.[9]

Fruit flavored e-liquids.

There is a possibility that inhalation, ingestion, or skin contact can expose people to high levels of nicotine.[34] Concerns with exposure to the e-liquids include leaks or spills and contact with contaminants in the e-liquid.[79] This may be especially risky to children, pregnant women, and nursing mothers.[34] The liquid quickly absorbs into the skin.[80] The nicotine in e-liquid can be hazardous to infants.[81] Even a portion of e-liquid may be lethal to a little child.[82] An excessive amount of nicotine for a child that is capable of being fatal is 0.1–0.2 mg/kg of body weight.[34] Less than a 1 tablespoon of contact or ingestion of e-liquid can cause nausea, vomiting, cardiac arrest, seizures, or coma.[83] An accidental ingestion of only 6 mg may be lethal to children.[38][84]

Children are susceptible to ingestion due to their curiosity and desire for oral exploration.[76] E-cigarettes are packed in colorful containers[74] and children may be attracted to the flavored liquids.[58] More youth-oriented flavors include "My Birthday Cake" or "Tutti Frutti Gumballs".[71] Many nicotine cartridges and bottles of liquid are not child-resistant to stop contact or accidental ingestion of nicotine by children.[11] "Open" e-cigarette devices, with a reﬁllable tank for e-liquids, are believed to be the biggest risk to young children.[83] It is recommended that e-cigarettes be kept in a safe place, where children and pets do not have access to them.[85]

Nicotine toxicity is of concern when e-cigarette solutions are swallowed intentionally by adults as a suicidal overdose.[40] Six people attempted suicide by injecting e-liquid.[41] One adolescent attempted suicide by swallowing the e-liquid.[18] Three deaths were reported to have resulted from swallowing or injecting e-liquid containing nicotine.[41] An excessive amount of nicotine for an adult that is capable of being fatal is 0.5–1 mg/kg of body weight.[34] An oral lethal dose for adults is about 30–60 mg.[53] However the widely used human LD50 estimate of around 0.8 mg/kg was questioned in a 2013 review, in light of several documented cases of humans surviving much higher doses; the 2013 review suggests that the lower limit resulting in fatal events is 500–1000 mg of ingested nicotine, which is equivalent to 6.5–13 mg/kg orally.[86] Reports of serious adverse effects associated with acute nicotine toxicity that resulting in hospitalization were very uncommon.[87] Death from intentional nicotine poisoning is very uncommon.[72] Clear labeling of devices and e-liquid could reduce unintentional exposures.[74] Child-proof packaging and directions for safe handling of e-liquids could minimize some of the risks.[81] In January 2016, the Child Nicotine Poisoning Prevention Act of 2015 was passed into law in the US,[88] which requires child-proof packaging.[89]

There was inconsistent labeling of the actual nicotine content on e-liquid cartridges from some brands,[5] and some nicotine has been found in ‘no nicotine' liquids.[21] A 2015 PHE report noted overall the labelling accuracy has improved.[90] Most inaccurately-labelled examples contained less nicotine than stated.[90] Due to nicotine content inconstancy, it is recommended that e-cigarette companies develop quality standards with respect to nicotine content.[24]

Because of the lack of production standards and controls, the pureness of e-liquid are generally not dependable, and testing of some products has shown the existence of harmful substances.[81] The German Cancer Research Center in Germany released a report stating that e-cigarettes cannot be considered safe, in part due to technical flaws that have been found.[38] This includes leaking cartridges, accidental contact with nicotine when changing cartridges, and potential of unintended overdose.[38] The Therapeutic Goods Administration (TGA) of Australia has stated that, "Some overseas studies suggest that electronic cigarettes containing nicotine may be dangerous, delivering unreliable doses of nicotine (above or below the stated quantity), or containing toxic chemicals or carcinogens, or leaking nicotine. Leaked nicotine is a poisoning hazard for the user of electronic cigarettes, as well as others around them, particularly children."[91]

Cannabinoid-containing e-liquids need lengthy, complex processing, some being available online without any toxicological and clinical evaluation.[92] It is thought that cannabinoids vaped at reduced temperatures is safer because it creates smaller amounts of toxicants than the burning of a hot cannabis cigarette.[92] The health effects of vaping cannabis formulations is mostly unknown.[92]

Most e-cigarettes use lithium batteries, the improper use of which may result in accidents.[9] It has been recommended that manufacturing quality standards be imposed in order to prevent such accidents.[9] Better product design and standards could probably reduce some of the risks.[79] Concern exists from risks associated with e-cigarette explosions for children and adults.[18]

Some batteries are not well designed, are made with poor quality components, or have defects.[1] Major injuries have occurred from battery explosions and fires.[5] A man endured a unilateral corneoscleral laceration with prolapsed iris tissue and hyphemato to the eye area when an e-cigarette exploded in his mouth.[93] A young man endured bilateral corneal burns to the eye area when an e-cigarette exploded near his chest.[93] E-cigarette explosions have resulted in burns, lost teeth, neck fractures, and battery acid contact to the face, mouth, and eyes.[93] A man died when charging an e-cigarette blown up and caught on fire next to oxygen equipment.[93] House and car fires and skin burns have resulted from some of the explosions.[1] The explosions were the result of extended charging, use of unsuitable chargers, or design flaws.[9] There is a possible risk to bystanders from e-cigarette explosions.[93] There is also a risk of property damage as a result of flammable materials catching on fire from an e-cigarette explosion.[93] The United States Fire Administration said that 25 fires and explosions were caused by e-cigarettes between 2009 and August 2014.[94] In the UK fire service call-outs had risen, from 43 in 2013 to 62 in 2014.[95] A 2015 PHE report concluded that the risks of fire from e-cigarettes "appear to be comparable to similar electrical goods".[96] Since e-cigarettes are not subjected to product safety testing, they may not have safety designs to avoid overheating, thermal runaway, and battery failure including fire and explosions.[93] There is inadequate product labeling to inform users of the possible serious harms.[93] The risk from serious adverse effects is low, but the aftermath may be disastrous in respect to an e-cigarette blast.[93] Victims have filed lawsuits to make restitution from the e-cigarette blasts.[41] Adverse effects may be under-reported because reports to the FDA is voluntary.[93]

In January 2015 the US Federal Aviation Administration issued a safety alert to air carriers that e-cigarettes should not be allowed in checked baggage after a review of fire safety issues, including two fires caused by e-cigarettes in checked baggage.[94][97] The International Civil Aviation Organization, a United Nations agency, also recommends prohibiting e-cigarettes in checked luggage.[94] A spokesman for the Tobacco Vapor Electronic Cigarette Association said that e-cigarettes do not pose a problem if they are packed correctly in static-free packaging, but that irresponsible people may sometimes pack them carelessly or tamper with them.[94] In-flight use of e-cigarettes is prohibited in the US.[97]

Users may alter many of the devices, such as using them to administer other drugs like cannabis.[5] E-liquid mixing is another way users tamper with e-cigarettes.[98] Mixing liquid in an unclean area runs the risk of contamination.[16] Users may add various flavorings and diluents.[98] Vodka or other forms of alcohol may also be added.[98] The addition of alcohol or nicotine could expose the user to more toxicants, especially when added in combinations.[98] Some ingredients in e-liquids could be flammable; this risk is more of concern for users who are inexperienced or do not use protective gear.[98] Users can adjust the voltage of some e-cigarettes.[98] The amount of vapor produced is controlled by the power of the battery, which has led some users to adjust their e-cigarettes to increase battery power to obtain a stronger nicotine "hit", but there is a small risk of battery explosion.[19] Some users add more or larger batteries to nonadjustable e-cigarettes, which may lead to battery leakage or explosion.[98] The extent to which teens are altering e-cigarettes, such as dripping the liquids onto the atomizer to get more nicotine intake, is not known.[18]

The long-term health impacts of e-cigarette use are unknown.[13] The long-term health impacts of the main chemicals nicotine and propylene glycol in the aerosol are not fully understood.[99] There is limited peer-reviewed data about the toxicity of e-cigarettes for a complete toxicological evaluation,[100] and their cytotoxicity is unknown.[15] The chemicals and toxicants included in e-cigarettes have not been completely disclosed and their safety is not guaranteed.[34] They are similar in toxicity to other nicotine replacement products,[101] but e-cigarettes manufacturing standards are variable standards, and many as a result are probably more toxic than nicotine replacement products.[102] The UK National Health Service noted that the toxic chemicals found by the FDA were at levels one-thousandth that of cigarette smoke, and that while there is no certainty that these small traces are harmless, initial test results are reassuring.[103] While there is variability in the ingredients and concentrations of ingredients in e-cigarette liquids, tobacco smoke contains thousands of chemicals, most of which are not understood and many of which are known to be harmful.[36]

Concerns about the carcinogenicity of e-cigarettes arise from both nicotine[28] and from other chemicals that may be in the vapor.[24] As regards nicotine, there is evidence from in vitro and animal research that nicotine may have a role as a tumor promoter, but carcinogenicity has not been demonstrated in vivo.[28] A 2014 Surgeon General of the United States report stated that the single relevant randomized trial "does not indicate a strong role for nicotine in promoting carcinogenesis in humans".[29] They concluded that "There is insufficient data to conclude that nicotine causes or contributes to cancer in humans, but there is evidence showing possible oral, esophageal, or pancreatic cancer risks".[29] Nicotine in the form of nicotine replacement products is less of a risk than compared to smoking,[29] and they have not been shown to be associated with cancer in the real world.[28]

There is no long-term research concerning the cancer risk related to the potentially small level of exposure to the identified carcinogens in the vapor.[8] In May 2014, Cancer Research UK stated that there are "very preliminary unpublished results that suggest that e-cigarettes promote tumour growth in human cells."[99] The e-cigarette vapors triggered DNA strand breaks and lowered cell survival in vitro.[41] A 2013 study found some samples of e-cigarette vapors had cytotoxic effects on cardiac muscle cells, though the effects were less than with cigarette smoke.[10] In October 2012, the World Medical Association stated, "Manufacturers and marketers of e-cigarettes often claim that use of their products is a safe alternative to smoking, particularly since they do not produce carcinogenic smoke. However, no studies have been conducted to determine that the vapor is not carcinogenic, and there are other potential risks associated with these devices."[104]

Chart showing various toxicants as measured in cigarette smoke and e-cigarette aerosol.[105]

Since nicotine-containing e-liquids are made from tobacco they may contain impurities like cotinine, anabasine, anatabine, myosmine and beta-nicotyrine.[13] The majority of e-cigarettes evaluated included carcinogenic tobacco-specific nitrosamines (TSNAs); heavy metals such as cadmium, nickel, and lead; and the carcinogen toluene.[34] However, in comparison to traditional cigarette smoke, the toxic substance levels identified in e-cigarette vapor were 9- to 450-fold less.[34] E-liquid with tin was cytotoxic.[12] E-cigarettes cannot be considered absolutely safe because there is no safe level for carcinogens.[106]

A 2014 review found higher levels of carcinogens and toxicants than in an FDA-approved nicotine inhaler, suggesting that FDA-approved devices may deliver nicotine more safely.[8] In 2014, The World Lung Foundation stated that "Researchers find that many e-cigarettes contain toxins, contaminants and carcinogens that conflict with the industry’s portrayal of its products as purer, healthier alternatives. They also find considerable variations in the amount of nicotine delivered by different brands. None of this information is made available to consumers so they really don’t know what they are ingesting, or how much."[107]

A 2014 review found "Various chemical substances and ultrafine particles known to be toxic, carcinogenic and/or to cause respiratory and heart distress have been identified in e-cigarette aerosols, cartridges, refill liquids and environmental emissions."[24] Few of the methods used to analyze the chemistry of e-cigarettes in the studies the review evaluated were validated.[24]

The propylene glycol molecule.

The primary base ingredients of the liquid solution is propylene glycol and glycerin.[5] About 20% to 27% of propylene glycol and glycerin-based liquid particles are inhaled.[108] The long-term effects of inhaled propylene glycol has not been studied,[58] and is unknown.[109] The effects of inhaled glycerin are unknown.[84] Being exposed to propylene glycol may cause irritation to the eyes and respiratory tract.[5] The risk from the inhalation of propylene glycol and glycerin is probably low.[13] Propylene glycol and glycerin have not been shown to be safe.[84] Some research states that propylene glycol emissions may cause respiratory irritation and raise the likelihood to develop asthma.[52] Long-term inhalation of propylene glycol indoors could increase risk to children to develop asthma.[38] To lessen the risks, most e-cigarettes companies began to use water and glycerin as replacement for propylene glycol.[52] The inhaled glycerin could cause lipoid pneumonia.[16]

Some e-cigarette products had acrolein identified in the aerosol.[13] It may be generated when glycerin is heated to higher temperatures.[13] Acrolein may induce irritation to the upper respiratory tract.[5] Acrolein levels were reduced by 60% in dual users and 80% for those that completely switched to e-cigarettes when compared to traditional cigarettes.[13] E-cigarettes vapor have been found to create oxidants and reactive oxygen species (OX/ROS).[19] OX/ROS could react with other substances in the vapor because they are highly reactive.[19] Although e-cigarettes have been found to contain OX/ROS at about 100 times less than in cigarette smoke, they probably induce meaningful biological effects.[19]

The toxicity of e-cigarettes and e-liquid can vary greatly, as there are differences in construction and materials in the delivery device, kind and origin of ingredients in the e-liquid, and the use or non-use of good manufacturing practices and quality control approaches.[100] If exposure of aerosols to propylene glycol and glycerin rises to levels that one would consider the exposure in association with a workplace setting, it would be sensible to investigate the health of exposed persons.[33] The short-term toxicity of e-cigarette use appears to be low, with the exception for some people with reactive airways.[21]

The essential propylene glycol and/or glycerin mixture may consist of natural or artificial substances to provide it flavor.[21] The cytotoxicity of e-liquids varies,[20] and contamination with various chemicals have been detected in the liquid.[21] Some liquids were very toxic and others had little or no cytotoxicity.[20] The cytotoxicity is mostly due to the amount and number of flavors added.[20] Since nicotine has a bitter taste, nicotine e-liquids contain chemicals to cover up the nicotine taste.[19] The liquids contain aromatic substances like tobacco, fruit, vanilla, caramel and coffee.[21] Generally, these additives are imprecisely described, using terms such as "vegetable flavoring".[21] Although they are approved for human consumption there are no studies on the short-term or long-term effects of inhaling them.[21] The safety of inhaling flavors is mostly unknown,[110] and their safety has not been determined by the Flavor and Extract Manufacturers Association.[41] In some cases e-liquids contain very large amounts of flavorings, which may cause irritation and inflammation on respiratory and cardiovascular systems.[69] Some flavors are regarded as toxic and a number of them resemble known carcinogens.[21] Some artificial flavors are known to be cytotoxic.[21] Unflavored vapor is less cytotoxic than flavored vapor.[23] A 2012 study demonstrated that in embryonic and adult cellular models, some substances of the vapor such as flavoring not found in tobacco smoke were cytotoxic.[111]

Cinnamaldehyde has been described as a highly cytotoxic material in vitro in cinnamon-flavored refill liquids.[1] Cinnamaldehyde have been identified as cytotoxic at the amount of about 400 times less than those allowed for use by the US Environmental Protection Agency.[9] Some e-liquids containing cinnamaldehyde stimulate TRPA1, which might induce effects on the lung.[19] E-liquids contain possibly toxic aldehydes and reactive oxygen species (ROS).[19] Many flavors are known aldehydes, such as anisaldehyde, cinnamaldehyde, and isovaleraldehyde.[19] The effects of aldehyde-containing flavors on pulmonary surfaces are unknown.[19] A 2012 study found butterscotch flavor was highly toxic with one liquid and two others had a low toxicity.[40] A 2014 in vitro study demonstrated that e-cigarette use of a "balsamic" flavor with no nicotine can activate the release of proinflammatory cytokine in lung epithelial cells and keratinocytes.[34] Some additives may be added to reduce the irritation on the pharynx.[84] The long-term toxicity is subject to the additives and contaminants in the e-liquid.[21]

Certain flavorings contain diacetyl and acetyl propionyl which give a buttery taste.[31] Diacetyl and acetyl propionyl are associated with bronchiolitis obliterans.[31] A 2015 review recommended for specific regulation of diacetyl and acetyl propionyl in e-liquid, which are safe when ingested but have been associated with respiratory harm when inhaled.[6] Both diacetyl and acetyl-propionyl have been found in concentrations above those recommended by the US National Institute for Occupational Safety and Health.[31] Diacetyl is normally found at lower levels in e-cigarettes than in traditional cigarettes.[31] Concerns exist that the flavors and additives in e-cigarettes might lead to diseases, including the popcorn lung.[112] The cardiovascular effects, including a vast range of flavorings and fragrances, is unknown.[113] The irritants butyl acetate, diethyl carbonate, benzoic acid, quinoline, bis(2-ethylhexyl) phthalate, and 2,6-dimethyl phenol were present as undeclared ingredients in the e-liquid.[62] The precise ingredients of e-cigarettes are not known.[114]

The IARC has categorized formaldehyde as a human carcinogen, and acetaldehyde is categorized as a potential carcinogenic to humans.[22] Aldehydes may cause harmful health effects; though, in the majority of cases, the amounts inhaled are less than with traditional cigarettes.[22] Many chemical compounds can inadvertently be produced from e-cigarettes, especially carbonyl compounds like formaldehyde, acetaldehyde, acrolein, and glyoxal by the chemical reaction of the e-liquid when the nichrome wire (heating element) is heated,[22] to high temperatures.[34] These compounds are frequently identified in e-cigarette aerosols.[22] The propylene glycol-containing liquids produced the most amounts of carbonyls in e-cigarette aerosols.[22] The levels of toxic chemicals in the vapor were found to be 1 to 2 orders of magnitude smaller than with cigarette smoke but greater than from a nicotine inhaler.[5] Nearly all e-cigarettes evaluated, toxic and irritation-causing carbonyls were identified.[34] Reports regarding the levels of toxic chemicals were inconsistent.[34] This includes a study showing that the levels of toxicants in e-cigarettes may be higher than with cigarette smoke.[34]

Battery output voltage influences the level of the carbonyl substances in the vapor.[22] A few new e-cigarettes let users boost the amount of vapor and nicotine provided by modifying the battery output voltage.[22] E-cigarettes with higher voltages (5.0 V[20]) can emit carcinogens including formaldehyde at levels comparable to cigarette smoke,[115] while reduced voltages (3.0 V[24]) generate aerosol with levels of formaldehyde and acetaldehyde roughly 13 and 807-fold less than in cigarette smoke.[22] "Dripping", where the liquid is dripped directly onto the atomizer, can create carbonyls including formaldehyde.[116]

A 2015 PHE report found that normal e-cigarette use generates very low levels of aldehydes.[26] Normal usage of e-cigarettes generates very low levels of formaldehyde,[23] and at normal settings they generate very low levels of formaldehyde.[26] Later-generation e-cigarettes used with higher power may generate equal or higher levels of formaldehyde than compared to smoking.[14][Notes 2] A 2015 review found that these levels were the result of overheating under test conditions that bear little resemblance to common usage.[25] A 2015 PHE report found that by applying maximum power and increasing the time the device is used on a puffing machine, e-liquids can thermally degrade and produce high levels of formaldehyde.[26] Users detect the "dry puff" and avoid it, and they concluded that "There is no indication that EC users are exposed to dangerous levels of aldehydes."[27] However, e-cigarette users may "learn" to overcome the unpleasant taste due to elevated aldehyde formation, when the nicotine craving is high enough.[19]

Possible side effects of nicotine.[117] A 2015 comparative risk analysis of drugs found the nicotine's margin of exposure (MOE) values were in a lower risk range than cocaine, heroine, and alcohol, whereas its MOE values was in a higher risk range than MDMA, methamphetamine, and methadone.[118] Shown above is the MOE for daily drug use from the analysis.[118]

Pregnant women, breastfeeding mothers, and the elderly are more sensitive to nicotine than other individuals.[110] There are safety issues with the nicotine exposure from e-cigarettes, which may cause addiction and other adverse effects.[24] Nicotine is regarded as a potentially lethal poison.[17] Concerns exist that vaping can be harmful by exposing users to toxic levels of nicotine.[17] At low amounts, it has a mild analgesic effect.[110] At high enough doses, nicotine may result in nausea, vomiting, diarrhea, salivation, bradyarrhythmia, and possibly seizures and hypoventilation.[35] However, at the low amount of nicotine provided by e-cigarettes fatal overdose from use is unlikely; in contrast, the potent amount of nicotine in e-cigarettes liquids may be toxic if it is accidentally ingested or absorbed via the skin.[17] The health effects of nicotine in infants and children are unclear.[35]

E-cigarettes provide nicotine to the blood quicker than nicotine inhalers.[53] The levels were above that of nicotine replacement product users.[17] E-cigarettes seem to have a pharmacokinetic nicotine profile closer to nicotine replacement products than with traditional cigarettes.[119] How efficiently different e-cigarettes give nicotine is unclear.[17]Serum cotinine levels are comparable to that of traditional cigarettes,[120] but are inharmonious and rely upon the user and the device.[8] Blood nicotine levels raised more gradually and took more time to get to peak concentration with e-cigarettes than with traditional cigarettes.[121]

When compared to traditional cigarettes older devices usually delivered low amounts of nicotine.[17] E-cigarette use can be associated with a substantial dispersion of nicotine, thus generating a plasma nicotine concentration which can be comparable to that of traditional cigarettes.[122] This is due to the minute nicotine particles in the vapor, which permit quick delivery into the bloodstream.[122] The nicotine delivered from e-cigarettes enters the body slower than traditional cigarettes.[123] Studies suggest that inexperienced users obtain moderate amounts of nicotine from e-cigarettes.[124] Concerns were raised over inconsistent amounts of nicotine delivered when drawing on the device.[125]

Later-generation e-cigarettes gives nicotine more effectively than first-generation e-cigarettes.[1] Later-generation models with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[17] E-cigarettes with stronger batteries heat solutions to higher temperatures, which may raise blood nicotine levels to those of traditional cigarettes.[40] Research suggests that experienced e-cigarettes users are able to get as much nicotine from e-cigarettes as traditional cigarettes.[17] Later-generation e-cigarettes containing sufficient nicotine elevates heart rate comparable to traditional cigarettes.[113]

The health effects of long-term nicotine use is unknown.[109] It may be decades before the long-term health effects of nicotine vapor inhalation is known.[126] It is not recommended for non-smokers.[9] Nicotine affects practically every cell in the body.[110] Nicotine can cause high blood pressure and abnormal heart rhythms.[107] Vapers that get a higher amount of blood nicotine are probably correlated with increased heart rates.[87] Nicotine may have adverse effects on lipids,[127] cause insulin resistance.[40] and can lower coronary blood flow.[113] Nicotine lowers estrogen levels and has been associated with early menopause in women.[107] Nicotine could have cancer-promoting properties, therefore long-term use may not be harmless.[98] Nicotine may result in neuroplasticity variations in the brain.[80] Nicotine could make cancer therapies less effective.[16]

Children are more sensitive to nicotine than adults.[110] In youth, nicotine may affect capabilities connected with higher cognitive function processes,[35] later achievement, as well as the chance of nicotine addiction for life.[107] The adolescents developing brain is especially sensitive to the harmful effects of nicotine.[82] A short period of regular or occasional nicotine exposure in adolescence exerts long-term neurobehavioral damage.[82] In August 2014, the American Heart Association noted that "e-cigarettes could fuel and promote nicotine addiction, especially in children."[40] A policy statement by the UK's Faculty of Public Health has stated, "A key concern for everyone in public health is that children and young people are being targeted by mass advertising of e-cigarettes. There is a danger that e-cigarettes will lead to young people and non-smokers becoming addicted to nicotine and smoking. Evidence from the US backs up this concern."[128]

There is limited evidence on the long-term exposure of metals.[9] Exposure to the levels and kinds of metals found in the aerosol relies upon the material and other manufacturing designs of the heating element.[40] E-cigarettes contain some contamination with small amounts of metals in the emissions but it is not likely that these amounts would cause a serious risk to the health of the user.[9] The device itself could contribute to the toxicity from the tiny amounts of silicate and heavy metals found in the liquid and vapor,[116] because they have metal parts that come in contact with the e-liquid.[9] Low levels of possibly harmful chromium, lead, and nickel metals have been found in the emissions.[40] Chromium and nickel nanoparticles have also been found.[5]

Metals may adversely affect the nervous system.[70] A 2013 review found metallic and nanoparticles are associated with respiratory distress and disease.[129] A 2014 review found considerable amounts of tin, metals, and silicate particles that came from various components of the e-cigarette were released into the aerosol, which result in exposure that could be higher than with cigarette smoke.[34] A 2013 study found metal particles in the aerosol were at levels 10-50 times less than permitted in inhalation medicines.[13] A 2014 review suggested that there is no evidence of contamination of the aerosol with metals that justifies a health concern.[33]

The risks to the lungs are not fully understood,[19] and concern exists regarding the negative effects on lung function.[130] There is limited evidence on the long-term health effects to the lungs.[14] Many ingredients used in e-liquids have not been examined in the lung.[19] The effects of e-cigarette use in respect to asthma and other respiratory diseases are unknown.[13] A 2015 review found e-cigarettes may induce acute lung disease.[14] A 2015 study found that e-cigarette vapors can induce oxidative stress in lung endothelial cells.[69] Constant lung inflammation as a result of the vapor could result in lung pathogenesis and induce serious diseases, including chronic obstructive pulmonary disease and fibrosis.[41] The limited evidence suggests that e-cigarettes produce less short-term effects on lung function than traditional cigarettes.[8] A 2014 case report observed the correlation between sub-acute bronchiolitis and vaping.[14] After quitting vaping the symptoms improved.[14]

The long-term effects regarding respiratory flow resistance are unknown.[60] E-cigarettes could harm the respiratory system.[21] The immediate effects of e-cigarettes after 5 minutes of use on pulmonary function resulted in considerable increases in resistance to lung airflow.[1] A 2013 review found an instant increase in airway resistance after using a single e-cigarette.[21] Any reported harmful effects to cardiovascular and respiratory functions after short-term use of e-cigarettes were appreciably milder in comparison to cigarette smoke.[9] When used in the short-term, an e-cigarette resulted in a rise of respiratory resistance comparatively to traditional cigarettes.[60] E-cigarette use could result in respiratory diseases among youth.[131]

There is no data available on the long-term cardiovascular effects.[8] There is no published research available on vaping and thrombosis, platelet reactivity, atherosclerosis, or blood vessel function.[14] The minute nicotine particles in the vapor could increase the risk of cardiac arrhythmias and hypertension which may put some users, particularly those with atherosclerosis or other cardiovascular risk factors, at significant risk of acute coronary syndrome.[122] Some case reports documented the possible cardiovascular adverse effects from using e-cigarettes, the majority associated was with improper use.[122] Even though e-cigarettes are anticipated to produce fewer harmful substances than traditional cigarettes, limited evidence supports they comparatively have a lessened raised cardiovascular risk.[122] E-cigarette use leads to sympathomimetic effects because of nicotine intake.[132] It is argued that there could be a risk for harmful effects, including tachycardia-induced cardiomyopathy.[132] E-cigarettes containing nicotine may have a lower cardiovascular effect than traditional cigarettes containing nicotine.[113] Short-term physiological effects include increases in blood pressure and heart rate.[14] A 2012 case report found a correlation between paroxysmal atrial fibrillation and vaping.[14]

Comparable to a traditional cigarette, e-cigarette particles are tiny enough to enter the alveoli, enabling nicotine absorption.[1] These particles are also tiny enough to go deep in the lungs and enter into the systemic circulation.[5] Local pulmonary toxicity may occur because metal nanoparticles can deposit in the lung's alveolar sacs.[5] E-cigarettes companies assert that the particulates produced by an e-cigarette are too tiny to be deposited in the alveoli.[53] Different devices generate different particle sizes and cause different depositions in the respiratory tract, even from the same nicotine liquid.[115] The aerosol production of e-cigarettes during vaping decreases, which requires a more forceful suction to create a similar volume of aerosol.[66] A more forceful suction could affect the deposition of substances into the lungs.[66] Reports in the literature have shown respiratory and cardiovascular effects by these smaller size particles, suggesting a possible health concern.[133]

Concern exists regarding the immunological effects of e-liquid, and analysis on animals demonstrate that e-liquid vapor, appear to have adverse effects on the immune system.[87] There were reports of e-cigarettes causing an immune system reaction involving inflammation of the gastrointestinal system.[41] Long-term use could increase the risk of tuberculosis.[12] It is possible that e-cigarettes could harm the periodontium because of the effects of nicotine on gum tissues and the immune system.[134] Some health effects associated with e-cigarette use can include recurring ulcerative colitis, lipoid pneumonia, acute eosinophilic pneumonitis, sub-acute bronchial toxicity, reversible cerebral vasoconstriction syndrome, and reversal of chronic idiopathic neutrophilia.[87]

Aerosol (vapor) exhaled by an e-cigarette user.

The aerosol of e-cigarettes is generated when the e-liquid reaches a temperature of roughly 100-250 °C within a chamber.[19] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[24] In physics, a vapor is a substance in the gas phase whereas an aerosol is a suspension of tiny particles of liquid, solid or both within a gas.[24] The aerosol is made-up of liquid sub-micron particles of condensed vapor,[135] which mostly consist of propylene glycol, glycerol, water, flavorings, nicotine, and other chemicals.[9] After a puff, inhalation of the aerosol travels from the device into the mouth and lungs.[24] The particle size distribution and sum of particles emitted by e-cigarettes are like traditional cigarettes, with the majority of particles in the ultrafine range.[5]

Various bottles of e-liquid.

After the aerosol is inhaled, it is exhaled.[24] Emissions from electronic cigarettes are not comparable to environmental pollution or cigarette smoke as their nature and chemical composition are completely different[9] The particles are larger, with the mean size being 600 nm in inhaled aerosol and 300 nm in exhaled vapor.[21] Bystanders are exposed to these particles from exhaled e-cigarette vapor.[5] There is a concern that some of the mainstream vapor exhaled by e-cigarette users can be inhaled by bystanders, particularly indoors, and have significant adverse effects.[34][129] Since e-cigarettes involve an aerosolization process, it is suggested that no meaningful amounts of carbon monoxide are emitted.[123] Thus, cardiocirculatory effects caused by carbon monoxide are not likely.[123] E-cigarette use by a parent might lead to inadvertent health risks to offspring.[35] E-cigarettes pose many safety concerns to children.[35] For example, indoor surfaces can accumulate nicotine where e-cigarettes were used, which may be inhaled by children, particularly youngsters, long after they were used.[35]

E-liquid is the mixture used in vapor products such as electronic cigarettes.[52] The main ingredients in the e-liquid usually are propylene glycol, glycerin, nicotine, and flavorings.[101] However, there are e-liquids sold without propylene glycol, nicotine, or flavors.[17][52][61] The liquid typically contains 95% propylene glycol and glycerin.[84] The flavorings may be natural or artificial.[21] About 8,000 flavors exist as of 2014.[136] There are many e-liquids manufacturers in the USA and worldwide.[137] While there are currently no US Food and Drug Administration (FDA) manufacturing standards for e-liquid, the FDA has proposed regulations that are expected to be finalized in late 2015.[138] Industry standards have been created and published by the American E-liquid Manufacturing Standards Association (AEMSA).[139]

Concerns exists regarding pregnant women exposure to e-cigarette vapor through direct use or via exhaled vapor.[5] No evidence have shown that e-cigarettes are safe to use for pregnant women.[140] No amount of nicotine is safe for pregnant women.[140] As of 2014[update], there are no conclusions on the possible hazards of pregnant women using e-cigarettes, and there is a developing research on the negative effects of nicotine on prenatal brain development.[8] E-cigarette are assumed to be dangerous to the fetus during pregnancy if e-cigarettes are used by the mother.[141] Nicotine is harmful to the growing fetus.[142] Nicotine accumulates in the fetus because it goes through the placenta.[38]

As of 2015[update], the long-term issues of e-cigarettes on both mother and unborn baby are unknown.[143] Prenatal nicotine exposure is associated with adverse effects on the growing fetus, including effects to normal growth of the endocrine, reproductive, respiratory, cardiovascular, and neurologic systems.[140] Prenatal nicotine exposure is associated with lower birth weights than other babies,[140]stillbirth,[82]sudden infant death syndrome, and alterations to normal brain development.[140] Prenatal nicotine exposure is associated with asthma and wheezing which may continue into adulthood.[140]Gestational age nicotine exposure is associated with many neurological deficits.[140] Prenatal exposure has been associated with obesity, diabetes, high cholesterol and high blood pressure in minors.[107] Prenatal nicotine exposure in females may lead toward early menarche.[140] An infant was born with necrotizing enterocolitis due to e-cigarette use during pregnancy.[41]

In what way the e-liquid ingredients could affect a fetus is unknown.[2] The toxicity of e-liquid flavorings was higher in embryonic stem cells compared to differentiated adult pulmonary fibroblasts, leading to concerns about pregnant women being exposed to the second-hand vapor.[109] There are concerns about the health impacts of pediatric exposure to second-hand and third-hand e-cigarette vapor.[18] The Surgeon General's 2014 report found "that nicotine adversely affects maternal and fetal health during pregnancy, and that exposure to nicotine during fetal development has lasting adverse consequences for brain development."[17] The belief that e-cigarettes are safer than traditional cigarettes could increase their use in pregnant women.[1] The toxic effects identified with e-cigarette refill liquids on stem cells may be interpreted as embryonic death or birth defects.[1] Since e-cigarettes are not validated as cessation tools, may contain nicotine at inconsistent levels and added ingredients that are possibly harmful, allowing e-cigarettes to be used among pregnant women to decrease smoking puts this group at considerable risk.[35] There is concern for breastfeeding women using e-cigarettes, due to the lack of data on propylene glycol transferring to breastmilk.[21]

There is limited information available on any environmental issues connected to the production, usage, and disposal of e-cigarette models that use cartridges.[37] As of 2014[update], no formal studies have been done to evaluate the environmental effects of making or disposing of any part of e-cigarettes including the batteries or nicotine production.[37] As of 2014[update], it is uncertain if the nicotine in e-liquid is United States Pharmacopeia-grade nicotine, a tobacco extract, or synthetic nicotine when questioning the environmental impact of how it is made.[37] It is not clear which manufacturing methods are used to make the nicotine used in e-cigarettes.[37] The emissions from making nicotine could be considerable from manufacturing if not appropriately controlled.[37] Some e-cigarette brands that use cartridges state their products are ‘eco-friendly’ or ‘green’, despite the absence of any supporting studies.[37] Some writers contend that such marketing may raise sales and increase e-cigarette interest, particularly among minors.[37]

It is unclear how many traditional cigarettes are comparable to using one e-cigarette that uses a cartridge for the average user.[37] Information is limited on energy and materials used for production of e-cigarettes versus traditional cigarettes, for comparable use.[37] E-cigarettes can be made manually put together in small factories, or they can be made in automated lines on a much bigger scale.[37] Larger plants will produce greater emissions to the surrounding environment, and thus will have a greater environmental impact.[37] Although some brands have begun recycling services for their e-cigarette cartridges and batteries, the prevalence of recycling is unknown, as is the prevalence of information provided by manufacturers on how to recycle disposable parts.[37] A 2014 review found "disposable e-cigarettes might cause an electrical waste problem."[123] Since the majority of e-cigarettes are reusable they are possibly more environmentally friendly than using single-use devices.[144] Compared to traditional cigarettes, e-cigarettes do not create litter in the form of discarded cigarette butts.[144] Traditional cigarette tend to end up in the ocean where they cause pollution.[144]

Marketing and advertisement affects the public’s perception of e-cigarettes.[109] Some tobacco users think vaping is safer than tobacco or other smoking cessation aids.[145] It is generally considered by users that e-cigarettes are safer than tobacco.[114] Many users think that e-cigarettes are healthier than traditional cigarettes for personal use or for other people.[58] Usually, only a small proportion of users are concerned about the possible adverse health effects or toxicity of e-cigarettes.[58] A 2014 worldwide survey found that 88% of respondents stated that vaping were less harmful than cigarette smoke and 11% believed that vaping were absolutely harmless.[146] A 2013 four-country survey found higher than 75% of current and former smokers think e-cigarettes are safer than traditional cigarettes.[1] The UK Action on Smoking and Health (ASH) found that in 2015, compared to the year before, "there has been a growing false belief that electronic cigarettes could be as harmful as smoking".[147] Among smokers who had heard of e-cigarettes but never tried them, this "perception of harm has nearly doubled from 12% in 2014 to 22% in 2015."[147] The UK ASH expressed concern that "The growth of this false perception risks discouraging many smokers from using electronic cigarettes to quit and keep them smoking instead which would be bad for their health and the health of those around them."[147]

A 2015 PHE report noted that in the US belief among respondents to a survey that vaping was safer than smoking cigarettes fell from 82% in 2010 to 51% in 2014.[148] The report blamed "misinterpreted research findings", attracting negative media coverage, for the growth in the "inaccurate" belief that e-cigarettes were as harmful as smoking,and concluded that "There is a need to publicise the current best estimate that using EC is around 95% safer than smoking".[duplication?][149]

^Tomashefski, Amy (2016). "The perceived effects of electronic cigarettes on health by adult users: A state of the science systematic literature review". Journal of the American Association of Nurse Practitioners: n/a–n/a. doi:10.1002/2327-6924.12358. ISSN 2327-6886. PMID 26997487.

^ abc"Electronic cigarette use among smokers slows as perceptions of harm increase". ASH. 22 May 2015. Retrieved 6 August 2015.

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

[Thorpe] Welcometo Beyond the Data.

I'm Dr.

Phoebe Thorpe, and herewith me today is Dr.

Brian King from CDC's Office onSmoking and Health.

Thank you for joining us Brian.

[King] Thanks somuch for having me.

It's a pleasure to be here.

[Thorpe] Our topictoday is E-cigarettes.

Can you tell us why they areconsidered a tobacco product? [King] Yes, so in the UnitedStates we regulate tobacco products through the US Foodand Drug Administration, and the way they describe atobacco product is any product that's made or derivedfrom tobacco.

And we know that the vastmajority of nicotine that's used in tobacco products,including e-cigarettes, is indeed derived from tobacco.

So since these productscontain nicotine, we consider them a tobaccoproduct in the United States.

[Thorpe] And E-cigarettesare little bit different than regular cigarettes.

Can you describe how they work? [King] Yeah, so E-cigarettes isshort for electronic cigarettes, but we know them by alot of different names.

And they can be calledthings like vapor products, hookah pens, vape pens, butthe bottom line is they're all really the same product.

And they work by containinga liquid that's heated which the user then inhales intotheir lungs, and it's important to note that this isn'ttechnically a vapor which is how peoplefrequently refer to.

It's actually an aerosol thatcontains small particles as well as various other ingredientsthat the user inhales, and so there's no combustion.

You're not burning anything, butthere is a heating of the liquid which turns into an aerosolwhich the user inhales.

And they can alsoexhale into the air as other bystandersare around them.

[Thorpe] And the aerosolis not just water vapor.

I mean, that's animportant part to understand because I get asked as aphysician about E-cigarettes, and the thing from the session that I found veryinteresting was the idea that were not reallycertain about the risks that flavorings addto E-cigarettes.

The one that was mentioned wasthe butter flavoring Diacetyl that has been associatedwith bronchiolitis obliterans or what's called popcorn lung,which is a deadly disease.

What more do we know aboutthe risks of E-cigarettes? [King] So our knowledgeabout what's contained in both the E-cigaretteliquid as well as the aerosol hascontinued to evolve over time that these products enteredthe United States marketplace in around 2007.

They didn't really start touptick in use until 2010, 2011.

But, since that time, we reallyincreased the amount of research into what these productscontain.

And what we can say isthat the aerosol admitted by these productsis not harmless.

We do know that the ingredients and the levels aresignificantly less dangerous than conventional cigarettes,but that doesn't mean that they're completelyrisk-free.

And so, some of theingredients we found in the E-cigaretteaerosol are things like ultrafine particulatethat can be inhaled very deep into the lungs, and alsoheavy metals that are found in the filaments of the deviceand are omitted in the aerosol, as well as, things likevolatile organic compounds.

But one of the most commoningredients is nicotine, and we know that nicotineis highly addictive.

But there's alsoevidence indicating that it can harm thedeveloping adolescent brain which really makes itimportant for youth to avoid these devices.

In addition to some of theseother harmful ingredients, we also know the flavorings.

And so, Diacetyl is justone, but there are a variety of different flavoringsthat are used that, although they may be safe toingest in things like food, we don't know what the risks are for inhaling thesedevices into the lungs.

You know, your gut can handlea lot more than your lungs, and that's reallyimportant when we look at the ingredientsin these products.

And finally, it's alsoimportant to remember that people are using a lotof things in E-cigarettes, and that includes otherpsychoactive substances like marijuana andTHC and others.

And so, when we are talkingabout youth in particular, the use of both the nicotinecontaining varieties as well as other varietiesfor other types of drugs are really apublic health concern.

[Thorpe] Okay.

But we have had somerecent good news about the youth meaningmiddle school and high school useof E-cigarettes.

Can you tell me about that? [King] Yes.

It's really a commendablepublic health accomplishment.

We started assessing E-cigaretteuse among youth in this country in 2011, and through 2015,we saw exponential increases in the use of this product.

And 2016 was the first time that we actually saw declineamong youth in this country, and that was really a resultof the coordinated efforts to not only educate thepublic about the harms of youth E-cigarette use but also implementingcommon sense strategies to not only prevent youth accessbut also to protect people from the aerosol andpublic environments and various other campaigns to educate peopleabout these products.

But, on balance, the badnews is that we still have over 2 million youth thatare using E-cigarettes, and they're now the mostcommonly used tobacco products used among US youth.

So we made great progress,but we really need to continue that momentum toreduce all forms of tobacco productuse among youth.

[Thorpe] So it's going down, butnot as lot much as we'd like.

So what's driving the use ofthe E-cigarettes in teens? [King] So there's avariety of factors that we believe are contributingto these increased rates of use among youth thatwe saw through 2015.

One of the most notable is theadvertising for these products.

We know that many of the themesand tactics that have been used to advertise conventionalcigarettes are frequently used for E-cigarettes.

And we also know thatthere's some media of for which conventional cigaretteadvertising is banned that is allowed forE-cigarettes.

Things like television.

And so, there's reallya prominent advertising of these products, and we know that it's reachingkids in particular.

About 18 million US youthreported being exposed to E-cigarette ads in 2014.

Another factor isflavorings, and we know, from the existing science, that flavorings can beparticularly appealing in terms of enticing youth and youngadults to use tobacco products.

And a variety of E-cigarettesare flavored, and we know, from the existing data, thatabout two thirds of youth who use these cigarettes reportusing flavored varieties, and flavors are the mostcommonly cited reason for why youth startedusing these products.

And so, in the end, wereally have a situation where you know the advertisingis bringing the horse to water.

The flavorings aregetting them to drink, and then the nicotine is keepingthem coming back for more.

And so, it's kind of aperfect storm in terms of the youth rates of this use.

But the good news is, we knowwhat works to prevent that.

And if we implement those commonsense public health strategies, we can continue to seethe declines that we saw within the past yearamong our nation's youth.

[Thorpe] And the realconcern is about nicotine and the teenage brain.

Can you just briefly tell mea little bit more about that? [King] Yeah.

So nicotine is found in thevast majority of E-cigarettes that are sold on the U.

S.

marketand, you know, nicotine we use in things like nicotinereplacement therapy among adults.

And it can be, youknow, an effective drug to help people quitconventional cigarette smoking.

But it's important to note thatthose are in very measured doses and weans the individual off of conventional cigarettesover time.

But nicotine is notnecessarily risk-free.

Particularly forvulnerable populations.

We know that nicotineis highly addictive, but there's also a growingbody of scientific evidence that was outlined in a recentSurgeon General's Report noting that nicotine exposure can harmthe developing adolescent brain.

And we know that thebrain continues to develop into young adulthood upthrough 25 or 26, and so, there's really implicationsfor not only youth use of these products butalso young adult use of any nicotine containingproduct.

And another thing to remember with nicotine is it'salso been shown to result in adverse health outcomesamong pregnant women in particularly fetal toxicity.

So there's also implications about pregnant womenusing any form of nicotine containing product,and so, it's really important for them to talk with theirphysician before they use any type of nicotine containingproduct including E-cigarettes.

[Thorpe] So is there a placethat physicians could go to learn a little bitmore about these parts with the E-cigarettesand the nicotine? [King] So there's many resourcesthat have been developed over the past fewyears, particularly as the sciences begun to grow.

And we have, you know,more concrete evidence about what works effectivelyto help warn people about these products and alsoprovide them scientific-based information to makeinformed decisions.

And in 2016, the U.

S.

SurgeonGeneral released a landmark report on E-cigarette useamong youth and young adults.

And as part of therelease of that report, there were severalmaterials including resources and provider cards to helphealth professionals really communicate to both childrenand adults about these products.

And so, in the context of youth, it really enforces theimportance of warning them about the dangersof these products.

Particularly with regardto the nicotine content.

And among adults, it's amore nuanced conversation about knowing that we dohave FDA approved medications to help people quit, and thoseshould really be the first line of defense to help you quit.

And if that doesn't work, youcan consider E-cigarettes, but in consultation withyour healthcare provider.

And right now, based onthe evidence we have, there is no conclusive evidencethat E-cigarettes are effective for long-term cessation, andso, it's really important to use those resources thatwe know are most effective to help you quitand in coordination with your healthcare provider.

[Thorpe] And then foryouth, where if parents or other adults wanted to knowmore about how they could talk to teens and young adults aboutthe risks of E-cigarettes, where would they find someinformation about that? [King] So as part of the releaseof the Surgeon General's Report, there's an excellent interactivewebsite that was coordinated with the release of that report, and it isE-cigarettes.

Surgeongeneral.

Gov.

And it has a varietyof information on both the reportitself as well as a public service announcementas well as informational cards for both parents andclinicians to educate our youth and young adults in particularabout the dangers and risks of using these products.

[Thorpe] That sounds like anexcellent place for our viewers to go and see whatthey can find out.

Thank you very muchfor joining us.

[King] Thank you verymuch for having me.

[Thorpe] And thankyou for joining us.

See you next monthon Beyond the Data.

E-Cigarette Forum 051817

UK

The entering into force of the requirements of the European tobacco products directive in Estonia made e-cigarette seller Nicorex Baltic destroy 19,000 bottles of e-cigarette liquid worth €135 000, as the packaging size did not meet the new requirements.

The liquids were actually in order, had undergone laboratory testing and met the new requirements, but their packaging did not have the necessary warnings on them and the boxes did not contain instructions.

Nicorex said that the transition period allowed by the government was too short, as the shelf life of the liquids was two years, but the length of the transition period only one year.

At the same time, Nicorex welcomed the requirement that the liquids have to undergo laboratory testing and that both the equipment and liquids must be registered in a single European database.

Nicorex described the restrictions concerning the size of packaging as unreasonable, as they increased the ecological footprint.

The transition period under the new tobacco law arising from the European tobacco products directive will end on May 20, after which the stricter requirements will apply to e-cigarettes in full.

Liquids can't be sold in containers bigger than 10 ml, they can't contain more nicotine than 20 milligrams per milliliter, and the vaporizer can't be bigger than 2 ml.

The packaging needs to include a leaflet, instructions, a batch number, a date, and a warning that nicotine is an addictive substance.

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

Disassembled parts of a first generation e-cigarette. A. LED light cover B. battery (also houses circuitry) C. atomizer (heating element) D. cartridge (mouthpiece) Parts of a second generation e-cigarette. An electronic cigarette is a battery-powered vaporizer.[1] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[3] When the user pushes a button,[4] or (in some variations) activates a pressure sensor by inhaling, the heating element then atomizes the liquid solution[5] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[7] The aerosol provides a flavor and feel similar to tobacco smoking.[1] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] Most cigalikes look like cigarettes but there is some variation in size.[11] Second generation devices are larger overall and look less like tobacco cigarettes.[12] Third generation devices include mechanical mods and variable voltage devices.[10] The fourth generation includes Sub ohm tanks and temperature control devices.[13] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[15] A later-generation box mod e-cigarette. Image courtesy of Ecigclick An e-cigarette is a handheld battery-powered vaporizer that simulates smoking, but without tobacco combustion.[1] Once the user inhales, the airflow activates the pressure sensor, and then the heating element atomizes the liquid solution.[5] Most devices have a manual push-button switch to turn them on or off.[16] E-cigarettes do not turn on by trying to "light" the device with a flame.[4] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] However, variable voltage devices can raise the temperature.[17] A glycerin-only liquid vaporizes at a higher temperature than a propylene glycol-glycerin liquid.[17] Rather than cigarette smoke, the user inhales an aerosol, commonly but inaccurately called vapor.[7] E-cigarettes do not create vapor between puffs.[18] Vaping is different than tobacco smoking, but there are some similarities with their behavioral habits, including the hand-to-mouth action and a vapor that looks like cigarette smoke.[1] E-cigarettes provide a flavor and feel similar to smoking.[1] A noticeable difference between the traditional cigarette and the e-cigarette is sense of touch.[1] A traditional cigarette is smooth and light but an e-cigarette is rigid, cold and slightly heavier.[1] Since e-cigarettes are more complex than traditional cigarettes, a learning curve is needed to use them correctly.[19] Compared to traditional cigarettes, the general e-cigarette puff time is much longer, and requires a more forceful suction than a regular cigarette.[20] The volume of vapor created by e-cigarette devices in 2012 declined with vaping.[1] Thus, to create the same volume of vapor increasing puff force is needed.[1] Later-generation e-cigarettes with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[21] Many e-cigarette versions include a voltage potentiometer to adjust the volume of vapor created.[4] The amount of vapor produced is controlled by the power from the battery, which has led some users to adjust their devices to increase battery power.[6] An ordinary cigarette compared to a "cigalike" e-cigarette E-cigarettes are usually approximately cylindrical, with many variations: pen-styles, tank-styles etc.[22] Some e-cigarettes look like traditional cigarettes, but others do not.[19] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] The only exception to this are mechanical e-cigarettes (mods) which contain no electronics and the circuit is closed by using a mechanical action switch.[23] E-cigarettes are sold in disposable or reusable variants.[8] Disposable e-cigarettes are discarded once the liquid in the cartridge is used up, while rechargeable e-cigarettes may be used indefinitely.[24] A disposable e-cigarette lasts to around 400 puffs.[25] Reusable e-cigarettes are refilled by hand or exchanged for pre-filled cartridges, and general cleaning is required.[4] A wide range of disposable and reusable e-cigarettes exist.[26] Disposable e-cigarettes are offered for a few dollars, and higher-priced reusable e-cigarettes involve an up-front investment for a starter kit.[19] Some e-cigarettes have a LED at the tip to resemble the glow of burning tobacco.[21] The LED may also indicate the battery status.[1] The LED is not generally used in personal vaporizers or mods.[2] First-generation e-cigarettes usually simulated smoking implements, such as cigarettes or cigars, in their use and appearance.[10] Later-generation e-cigarettes often called mods, PVs (personal vaporizer) or APVs (advanced personal vaporizer) have an increased nicotine-dispersal performance,[10] house higher capacity batteries, and come in various shapes such as metal tubes and boxes.[27] They contain silver, steel, metals, ceramics, plastics, fibers, aluminum, rubber and spume, and lithium batteries.[28] A growing subclass of vapers called cloud-chasers configure their atomizers to produce large amounts of vapor by using low-resistance heating coils.[29] This practice is known as cloud-chasing.[30] Many e-cigarettes are made of standardized replaceable parts that are interchangeable between brands.[31] A wide array of component combinations exists.[32] Many e-cigarettes are sold with a USB charger.[33] E-cigarettes that resemble pens or USB memory sticks are also sold for those who may want to use the device unobtrusively.[34] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] Various types of e-cigarettes. First-generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] The three parts of a cigalike e-cigarette initially were a cartridge, an atomizer, and a battery.[35] A cigalike e-cigarette currently contains a cartomizer (cartridge atomizer), which is connected to a battery.[35] Most cigalikes look like cigarettes but there is some variation in size.[35] They may be a single unit comprising a battery, coil and filling saturated with e-juice in a single tube to be used and discarded after the battery or e-liquid is depleted.[10] They may also be a reusable device with a battery and cartridge called a cartomizer.[12] The cartomizer cartridge can be separated from the battery so the battery can be charged and the empty cartomizer replaced when the e-juice runs out.[10] The battery section may contain an electronic airflow sensor triggered by drawing breath through the device.[12] Other models use a power button that must be held during operation.[12] An LED in the power button or on the end of the device may also show when the device is vaporizing.[36] Charging is commonly accomplished with a USB charger that attaches to the battery.[37] Some manufacturers also have a cigarette pack-shaped portable charging case (PCC), which contains a larger battery capable of recharging the individual e-cigarette batteries.[38] Reusable devices can come in a kit that contains a battery, a charger, and at least one cartridge.[38] Varying nicotine concentrations are available and nicotine delivery to the user also varies based on different cartomizers, e-juice mixtures, and power supplied by the battery.[22] These manufacturing differences affect the way e-cigarettes convert the liquid solution to an aerosol, and thus the levels of ingredients, that are delivered to the user and the surrounding air for any given liquid.[22] First-generation e-cigarettes use lower voltages, around 3.7 V.[39] Second-generation PV. Second generation devices tend to be used by people with more experience.[12] They are larger overall and look less like tobacco cigarettes.[12] They usually consist of two sections, basically a tank and a separate battery. Their batteries have higher capacity, and are not removable.[10] Being rechargeable, they use a USB charger that attaches to the battery with a threaded connector. Some batteries have a "passthrough" feature so they can be used even while they are charging.[40][41] Second-generation e-cigarettes commonly use a tank or a "clearomizer".[12] Clearomizer tanks are meant to be refilled with e-juice, while cartomizers are not.[10] Because they're refillable and the battery is rechargeable, their cost of operation is lower.[10] Hovever, they can also use cartomizers, which are pre-filled only.[10] Some cheaper battery sections use a microphone that detects the turbulence of the air passing through to activate the device when the user inhales.[42] Other batteries like the eGo style can use an integrated circuit, as well as a button for manual activation. The LED shows battery status.[42] The power button can also switch off the battery so it is not activated accidentally.[43] Second generation e-cigarettes may have lower voltages, around 3.7 V.[39] However, adjustable-voltage devices can be set between 3 V and 6 V.[44] Third-generation PV. The third-generation includes mechanical mods and variable voltage devices.[45][46] Battery sections are commonly called "mods," referencing their past when user modification was common.[10] Mechanical mods do not contain integrated circuits.[46] They are commonly cylindrical or box-shaped, and typical housing materials are wood, aluminium, stainless steel, or brass.[47] A larger "box mod" can hold bigger and sometimes multiple batteries.[47] Mechanical mods and variable devices use larger batteries than those found in previous generations.[48] Common battery sizes used are 18350, 18490, 18500 and 18650.[49] The battery is often removable,[46] so it can be changed when depleted. The battery must be removed and charged externally.[46] Variable devices permit setting wattage, voltage, or both.[40][46] These often have a USB connector for recharging; some can be used while charging, called a "passthrough" feature.[40][50] Mechanical mods do not contain integrated circuits.[46] The power section may include additional options such as screen readout, support for a wide range of internal batteries, and compatibility with different types of atomizers.[12] Third-generation devices can have rebuildable atomizers with different wicking materials.[10][12] These rebuildables use handmade coils that can be installed in the atomizer to increase vapor production.[48] Hardware in this generation is sometimes modified to increase power or flavor.[51] The larger battery sections used also allow larger tanks to be attached that can hold more e-liquid.[47] Recent devices can go up to 8 V, which can heat the e-liquid significantly more than earlier generations.[39] A fourth-generation e-cigarette became available in the U.S. in 2014.[21] Fourth-generation e-cigarettes can be made from stainless steel and pyrex glass, and contain very little plastics.[13] Included in the fourth-generation are Sub ohm tanks and temperature control devices.[13] An e-cigarette atomizer with the coil (heating element) in view. An atomizer comprises a small heating element that vaporizes e-liquid and a wicking material that draws liquid onto the coil.[3] Along with a battery and e-liquid the atomizer is the main component of every personal vaporizer.[12] A small length of resistance wire is coiled around the wicking material and connected to the integrated circuit, or in the case of mechanical devices, the atomizer is connected directly to the battery through either a 510, 808, or ego threaded connector.[52] 510 being the most common.[52] When activated, the resistance wire coil heats up and vaporizes the liquid, which is then inhaled by the user.[53] The electrical resistance of the coil, the voltage output of the device, the airflow of the atomizer and the efficiency of the wick all affect the vapor coming from the atomizer.[54] They also affect the vapor quantity or volume yielded.[54] Atomizer coils made of kanthal usually have resistances that vary from 0.4Ω (ohms) to 2.8Ω.[54] Coils of lower ohms have increased vapor production but could risk fire and dangerous battery failures if the user is not knowledgeable enough about electrical principles and how they relate to battery safety.[55] Wicking materials vary from one atomizer to another.[56] "Rebuildable" or "do it yourself" atomizers can use silica, cotton, rayon, porous ceramic, hemp, bamboo yarn, oxidized stainless steel mesh and even wire rope cables as wicking materials.[56] A 45mm length, extra-long cartomizer. The cartomizer was invented in 2007, integrating the heating coil into the liquid chamber.[57] A "cartomizer" (a portmanteau of cartridge and atomizer.[58]) or "carto" consists of an atomizer surrounded by a liquid-soaked poly-foam that acts as an e-liquid holder.[3] They can have up to 3 coils and each coil will increase vapor production.[3] The cartomizer is usually discarded when the e-liquid starts to taste burnt, which usually happens when the e-cigarette is activated with a dry coil or when the cartomizer gets consistently flooded (gurgling) because of sedimentation of the wick.[3] Most cartomizers are refillable even if not advertised as such.[3][59] Cartomizers can be used on their own or in conjunction with a tank that allows more e-liquid capacity.[3] The portmanteau word "cartotank" has been coined for this.[60] When used in a tank, the cartomizer is inserted in a plastic, glass or metal tube and holes or slots have to be punched on the sides of the cartomizer so liquid can reach the coil.[3] eGo style e-cigarette with a top-coil clearomizer. Silica fibers are hanging down freely inside of the tank, drawing e-liquid by capillary action to the coil that is located directly under the mouthpiece. The clearomizer was invented in 2009 that originated from the cartomizer design.[57] It contained the wicking material, an e-liquid chamber, and an atomizer coil within a single clear component.[57] This allows the user to monitor the liquid level in the device.[57] Clearomizers or "clearos", are like cartotanks, in that an atomizer is inserted into the tank.[61] There are different wicking systems used inside clearomizers.[3] Some rely on gravity to bring the e-liquid to the wick and coil assembly (bottom coil clearomizers for example) and others rely on capillary action or to some degree the user agitating the e-liquid while handling the clearomizer (top coil clearomizers).[3][62] The coil and wicks are typically inside a prefabricated assembly or "head" that is replaceable by the user.[63] Clearomizers are made with adjustable air flow control.[64] Tanks can be plastic or borosilicate glass.[65] Some flavors of e-juice have been known to damage plastic clearomizer tanks.[65] Box mod e-cigarette fitted with a rebuildable dripping atomizer (RDA). A view of the RDA deck showing the wicks and coils, juice is dripped into a hopper where the wicks rest as well as atop the coil assembly. A rebuildable atomizer or an RBA is an atomizer that allows the user to assemble or "build" the wick and coil themselves instead of replacing them with off-the-shelf atomizer "heads".[10] They are generally considered advanced devices.[66] They also allow the user to build atomizers at any desired electrical resistance.[10] These atomizers are divided into two main categories; rebuildable tank atomizers (RTAs) and rebuildable dripping atomizers (RDAs).[67] Rebuildable tank atomizers (RTAs) have a tank to hold liquid that is absorbed by the wick.[68] They can hold up to 4ml of e-liquid.[69] The tank can be either plastic, glass, or metal.[65] One form of tank atomizers was the Genesis style atomizers.[68] They can use ceramic wicks, stainless steel mesh or rope for wicking material.[68] The steel wick must be oxidized to prevent arcing of the coil.[68] Another type is the Sub ohm tank.[69] These tanks have rebuildabe or RBA kits.[69] They can also use coilheads of 0.2ohm 0.4hom and 0.5ohm.[69] These coilheads can have stainless steel coils.[70] Rebuildable dripping atomizers (RDAs) are atomizers where the e-juice is dripped directly onto the coil and wick.[71] The common nicotine strength of e-liquids used in RDA's is 3 mg and 6 mg.[71] Liquids used in RDA's tend to have more vegetable glycerin.[71] They typically consist only of an atomizer "building deck", commonly with three posts with holes drilled in them, which can accept one or more coils.[51] The user needs to manually keep the atomizer wet by dripping liquid on the bare wick and coil assembly, hence their name.[71] Kanthal wire is commonly used in both RDA's and RTA's.[71] They can also use nickel wire or titanium wire for temperature control.[71] Variable devices are variable wattage, variable voltage or both.[40][46] Variable power and/or variable voltage have a electronic chip allowing the user to adjust the power applied to the heating element.[12][46] The amount of power applied to the coil affects the heat produced, thus changing the vapor output.[12][32] Greater heat from the coil increases vapor production.[32] Variable power devices monitor the coil's resistance and automatically adjust the voltage to apply the user-specified level of power to the coil.[72] Recent devices can go up to 8 V.[39] They are often rectangular but can also be cylindrical.[47] They usually have a screen to show information such as voltage, power, and resistance of the coil.[73] To adjust the settings, the user presses buttons or rotates a dial to turn the power up or down.[32] Some of these devices include additional settings through their menu system such as: atomizer resistance meter, remaining battery voltage, puff counter, and power-off or lock.[74] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[4] Smaller devices contain smaller batteries and are easier to carry but typically require more repeated recharging.[4] Some e-cigarettes use a long lasting rechargeable battery, a non-rechargeable battery or a replaceable battery that is either rechargeable or non-rechargeable for power.[26] Some companies offer portable chargeable cases to recharge e-cigarettes.[26] Nickel-cadmium (NiCad), nickel metal-hydride (NiMh), lithium ion (Li-ion), alkaline and lithium polymer (Li-poly), and lithium manganese (LiMn) batteries have been used for the e-cigarettes power source.[26] PV with variable and regulated power offering battery protection. Temperature control devices allow the user to set the temperature.[71] There is a predictable change to the resistance of a coil when it is heated.[75] The resistance changes are different for different types of wires, and must have a high temperature coefficient of resistance.[75] Temperature control is done by detecting that resistance change to estimate the temperature and adjusting the voltage to the coil to match that estimate.[76] Nickel, titanium, NiFe alloys, and certain grades of stainless steel are common materials used for wire in temperature control.[71] The most common wire used, kanthal, cannot be used because it has a stable resistance regardless of the coil temperature.[75] Nickel was the first wire used because of it has the highest coefficient of the common metals.[75] Mechanical PV with a rebuildable atomizer. The temperature can be adjusted in Celsius or Fahrenheit.[77] The DNA40 and SX350J are common control boards used in temperature control devices.[78] Temperature control can stop dry wicks from burning, or e-liquid overheating.[78] Mechanical PVs or mechanical "mods", often called "mechs", are devices without integrated circuits, electronic battery protection, or voltage regulation.[46] They are activated by a switch.[71] They rely on the natural voltage output of the battery and the metal that the mod is made of often is used as part of the circuit itself.[79] The term "mod" was originally used instead of "modification".[10] Users would modify existing hardware to get better performance, and as an alternative to the e-cigarettes that looked like traditional cigarettes.[32] Users would also modify other unrelated items like flashlights as battery compartments to power atomizers.[32][47] The word mod is often used to describe most personal vaporizers.[3] Mechanical PVs have no power regulation and are unprotected.[71] Because of this ensuring that the battery does not over-discharge and that the resistance of the atomizer requires amperage within the safety limits of the battery is the responsibility of the user.[79]

Safety of electronic cigarettes

UK

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful than cigarettes but may still be dangerous. Under which circumstances should a person use electronic cigarettes? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

Additionally, they're being marketed to children.

Do E-cigs Impact Society?

Are electronic cigarettes safe to use in public?

Many countries, states, cities, companies, bars and restaurants, and other organizations are banning the use of electronic cigarettes. There are a variety of reasons for their ban.

In 'Drugs And Society' by Glen R. Hanson, Peter J. Venturelli, Annette E. Fleckenstein, the implications the use of drugs has on society is explored in detail. The findings are quite fascinating.

De-icing your lungs?

Many articles about e-cigarettes will focus on the legality of their use and sale, their addictiveness, and the demographics who uses them. What few articles mention though, is what the ingredients in electronic cigarettes are and why you may not want them in your body.

Propylene glycol is basically plastic. Actually it's an additive for manufacturing plastic. The single largest use of PG is for the production of unsaturated polyester resins. It is also used as a humectant (an additive that keeps something moist), and as a preservative for food and tobacco. Mmm, yummy.

Propylene glycol has similar thermal properties to ethylene glycol in that it can lower the freezing point of water when added to it. As a result, propylene glycol is often used as aircraft de-icing fluid, according to Steve Ritter's article What's That Stuff?" on the C&EN website.

Another fun fact: disclosure of which chemicals are in any given electronic cigarette are often not made available by manufacturers or retailers. The most recent information regarding the health effects on humans of acute exposure to propylene glycol by inhalation is from 2002. Please find this information made available by the EPA at the bottom of this article.

Formaldehyde in Cigarettes; Nicotine could Kill a Child

You are probably not a doctor (although, you might be), and you probably rely on the advice of experts for medical information and health recommendations. Using your best judgement, do you think that electronic cigarettes are safe to use? Would you recommend using an electronic cigarette to your friends and family? How about your kids?

Take a look at this video from reports in France. It says that e-cigarettes contain level of formaldehyde near that of tobacco cigarettes. What? I do not know if that information is true, but if it is, it's not good!

The reports urge people to understand that electronic cigarettes are not healthy. Furthermore, the reports say that some models of e-cigarette do not have protective safety caps even though they have enough nicotine to kill a child. That is a liability. Yikes!

Quick facts

The molecular formula for propylene glycol is C3H8O2

It is a clear and colorless liquid and is non-corrosive

It is unknown whether or not is adversely affects human health

It is a main ingredient in electronic cigarettes and windshield washer liquid

Using it, you might look cool to some people (but they are pathetic losers)

Plastic boogers – your snot turns white and is now made of plastic

Ready for the formula? It's CH3CHOHCH2OH

The molecular formula for propylene glycol is C3H8O2. It is a clear and colourless liquid and is non-corrosive.

C3H8O2 can accumulate in your body from the use of shampoo, deodorant, moisturisers and creams, pain medication and a host of food products. So there's probably already enough in there without the use of e-cigs.

E-cigarettes offer you the opportunity to pay money to suck PG directly into the center of your body.

What Should You Do About It?

At best, e-cigarettes are neutral for your health and at worst they are detrimental to your health. How bad for you are they?

You'll need good luck if you are currently using an electronic cigarette! Because the health effects are largely unknown, using an e-cig is a gamble and you'll need all the luck you can get.

Enjoy!

Propylene Glycol Reference from the EPA

It looks like a few people have looked into it before. It's surprising there's not a lot of available data as to the effects of inhalation on humans. Shocking!

Burkhart, J., Piacitelli, C., Schwegler-Berry, D., and Jones, W. Environmental study of nylon flocking process. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH PART A; 57 (1).1999.1-23.AB - BIOSIS COPYRIGHT: BIOL ABS.Environmental measurements for a variety of gas, particulate, and microbiological agents have been made in order to characterize exposures associated with the nylon flocking process.Of all agents measured, particulate is the predominant exposure.Levels of total particulate ranged from 0.1 to 240 mg/m3 ( x = 11.4 mg/m3).Average respirable particulate was 2.2 mg/m3, ranging from 0.5 to 39.9 mg/m3.Highest levels of particulates were found in the flocking room, and direct reading dust measuremen veral of which were linked directly to the process.Of special interest were elongated respirable particles, which by microscopic analysis, complemented with melting-point determination, were found to be shreds of nylon. 1999. Code: 8

Corley, R. A., Crissman, J. W., Redmond, J. M., McGuirk, R. J., Cieszlak, F. S., and Stott, W. T. Adaptive Metabolic and Pathologic Changes following Chronic Inhalation of Propylene Glycol Monomethyl Ether in Rats and Mice. Occupational Hygiene, Vol.2, Nos.1-6, pages 319-328, 24 references, 1996 AB - The temporal relationships between propylene-glycol-monomethyl-ether (107982) (PGME) induced metabolic and morphological changes in rats and mice which have been chronically exposed to up to 3,000 parts per million (ppm) of PGME vapors were characterized.B6C3F1-mice and F344-rats were exposed to 300, 1,000, or 3,000ppm for 6 hours a day, 5 days a week, for up to 2 years.Results indicated that there is potential for adaptive biochemical and cellular changes in response to chemical exposure to modify the toxicity of PGME in rats and mice.Nearly all inhaled PGME was absorbed, resulting in high systemic levels of PGME.These levels may result in central nervous system depression and the clinically observable sedation of exposed animals.A disruption in male rats was noted in the processing of alpha2micro-globulin resulting in mild degenerative effects in renal tubule epithelial cells.The pronounced sedation of rats and mice exposed to 3,000ppm resolved by the second week of exposure.The induction of O-dealkylase activity in these animals suggests an increase in the potential of metabolized PGME via its major metabolic route to propylene-glycol and then to carbon-dioxide.Exposed animals may also have effectively enhanced PGME metabolism by increasing the number of hepatocytes in response to PGME exposure resulting in the increase in liver weights.Clearly defined, treatment related renal effects were only observed in male rats.The authors conclude that high concentrations of PGME cause an adaptive hepatic response in both sexes of rats and mice that is partially reversed in rats. 1996. Code: 8

Ishiwata, H., Nishijima, M., Fukasawa, Y., Ito, Y., and Yamada, T. Evaluation of the contents of BHA, BHT, propylene glycol, and sodium saccharin in foods and estimation of daily intake based on the results of official inspection in Japan in fiscal year 1994. Journal of the Food Hygienic Society of Japan; 39 (2).1998.89-100. 1998. Code: 8

Kucherenko, Y. U. and Moiseev, V. A. The use of 1H-NMR spectroscopy and refractometry for investigation of the distribution of nonelectrolytes of N-alcohol series between human red blood cells and extracellular medium. Membr Cell Biol 13(5):633-44. 2000. Code: 8

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful in the UK than cigarettes but may still be dangerous. Under which circumstances should a person use ecigs? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

UK Electronic Cigarettes and E-Liquid

E-cigs vs. T-cigs

Electronic cigarettes may be less harmful than cigarettes but may still be dangerous. Under which circumstances should a person use electronic cigarettes? Will they fill your body with plastic?

Electronic cigarettes can contain propylene glycol or vegetable glycerine with nicotine (and in at least two cases polyethylene glycol 400) to form a solution that when heated by an atomizer, produces a visible vapour that provides nicotine to the bloodstream via the lungs when inhaled.

Electronic cigarettes have not been studied enough by scientists in laboratories to form conclusive evidence that their use is either beneficial or harmful to humans. However, some are concerned that unknown side-effects could occur with continuous, consistent use of electronic cigarettes, including cancer.

Behaviour surrounding their use is worrisome because e-cigs are being used habitually by a percentage of non-smokers who otherwise would not use nicotine, they may seem attractive to children, they are not closely regulated, and their use makes it very easy to overdose on nicotine even for experienced smokers.

Additionally, they're being marketed to children.

Do E-cigs Impact Society?

Are electronic cigarettes safe to use in public?

Many countries, states, cities, companies, bars and restaurants, and other organizations are banning the use of electronic cigarettes. There are a variety of reasons for their ban.

In 'Drugs And Society' by Glen R. Hanson, Peter J. Venturelli, Annette E. Fleckenstein, the implications the use of drugs has on society is explored in detail. The findings are quite fascinating.

De-icing your lungs?

Many articles about e-cigarettes will focus on the legality of their use and sale, their addictiveness, and the demographics who uses them. What few articles mention though, is what the ingredients in electronic cigarettes are and why you may not want them in your body.

Propylene glycol is basically plastic. Actually it's an additive for manufacturing plastic. The single largest use of PG is for the production of unsaturated polyester resins. It is also used as a humectant (an additive that keeps something moist), and as a preservative for food and tobacco. Mmm, yummy.

Propylene glycol has similar thermal properties to ethylene glycol in that it can lower the freezing point of water when added to it. As a result, propylene glycol is often used as aircraft de-icing fluid, according to Steve Ritter's article What's That Stuff?" on the C&EN website.

Another fun fact: disclosure of which chemicals are in any given electronic cigarette are often not made available by manufacturers or retailers. The most recent information regarding the health effects on humans of acute exposure to propylene glycol by inhalation is from 2002. Please find this information made available by the EPA at the bottom of this article.

Formaldehyde in Cigarettes; Nicotine could Kill a Child

You are probably not a doctor (although, you might be), and you probably rely on the advice of experts for medical information and health recommendations. Using your best judgement, do you think that electronic cigarettes are safe to use? Would you recommend using an electronic cigarette to your friends and family? How about your kids?

Take a look at this video from reports in France. It says that e-cigarettes contain level of formaldehyde near that of tobacco cigarettes. What? I do not know if that information is true, but if it is, it's not good!

The reports urge people to understand that electronic cigarettes are not healthy. Furthermore, the reports say that some models of e-cigarette do not have protective safety caps even though they have enough nicotine to kill a child. That is a liability. Yikes!

Quick facts

The molecular formula for propylene glycol is C3H8O2

It is a clear and colorless liquid and is non-corrosive

It is unknown whether or not is adversely affects human health

It is a main ingredient in electronic cigarettes and windshield washer liquid

Using it, you might look cool to some people (but they are pathetic losers)

Plastic boogers – your snot turns white and is now made of plastic

Ready for the formula? It's CH3CHOHCH2OH

The molecular formula for propylene glycol is C3H8O2. It is a clear and colourless liquid and is non-corrosive.

C3H8O2 can accumulate in your body from the use of shampoo, deodorant, moisturisers and creams, pain medication and a host of food products. So there's probably already enough in there without the use of e-cigs.

E-cigarettes offer you the opportunity to pay money to suck PG directly into the center of your body.

What Should You Do About It?

At best, e-cigarettes are neutral for your health and at worst they are detrimental to your health. How bad for you are they?

You'll need good luck if you are currently using an electronic cigarette! Because the health effects are largely unknown, using an e-cig is a gamble and you'll need all the luck you can get.

Enjoy!

Propylene Glycol Reference from the EPA

It looks like a few people have looked into it before. It's surprising there's not a lot of available data as to the effects of inhalation on humans. Shocking!

Burkhart, J., Piacitelli, C., Schwegler-Berry, D., and Jones, W. Environmental study of nylon flocking process. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH PART A; 57 (1).1999.1-23.AB - BIOSIS COPYRIGHT: BIOL ABS.Environmental measurements for a variety of gas, particulate, and microbiological agents have been made in order to characterize exposures associated with the nylon flocking process.Of all agents measured, particulate is the predominant exposure.Levels of total particulate ranged from 0.1 to 240 mg/m3 ( x = 11.4 mg/m3).Average respirable particulate was 2.2 mg/m3, ranging from 0.5 to 39.9 mg/m3.Highest levels of particulates were found in the flocking room, and direct reading dust measuremen veral of which were linked directly to the process.Of special interest were elongated respirable particles, which by microscopic analysis, complemented with melting-point determination, were found to be shreds of nylon. 1999. Code: 8

Corley, R. A., Crissman, J. W., Redmond, J. M., McGuirk, R. J., Cieszlak, F. S., and Stott, W. T. Adaptive Metabolic and Pathologic Changes following Chronic Inhalation of Propylene Glycol Monomethyl Ether in Rats and Mice. Occupational Hygiene, Vol.2, Nos.1-6, pages 319-328, 24 references, 1996 AB - The temporal relationships between propylene-glycol-monomethyl-ether (107982) (PGME) induced metabolic and morphological changes in rats and mice which have been chronically exposed to up to 3,000 parts per million (ppm) of PGME vapors were characterized.B6C3F1-mice and F344-rats were exposed to 300, 1,000, or 3,000ppm for 6 hours a day, 5 days a week, for up to 2 years.Results indicated that there is potential for adaptive biochemical and cellular changes in response to chemical exposure to modify the toxicity of PGME in rats and mice.Nearly all inhaled PGME was absorbed, resulting in high systemic levels of PGME.These levels may result in central nervous system depression and the clinically observable sedation of exposed animals.A disruption in male rats was noted in the processing of alpha2micro-globulin resulting in mild degenerative effects in renal tubule epithelial cells.The pronounced sedation of rats and mice exposed to 3,000ppm resolved by the second week of exposure.The induction of O-dealkylase activity in these animals suggests an increase in the potential of metabolized PGME via its major metabolic route to propylene-glycol and then to carbon-dioxide.Exposed animals may also have effectively enhanced PGME metabolism by increasing the number of hepatocytes in response to PGME exposure resulting in the increase in liver weights.Clearly defined, treatment related renal effects were only observed in male rats.The authors conclude that high concentrations of PGME cause an adaptive hepatic response in both sexes of rats and mice that is partially reversed in rats. 1996. Code: 8

Ishiwata, H., Nishijima, M., Fukasawa, Y., Ito, Y., and Yamada, T. Evaluation of the contents of BHA, BHT, propylene glycol, and sodium saccharin in foods and estimation of daily intake based on the results of official inspection in Japan in fiscal year 1994. Journal of the Food Hygienic Society of Japan; 39 (2).1998.89-100. 1998. Code: 8

Kucherenko, Y. U. and Moiseev, V. A. The use of 1H-NMR spectroscopy and refractometry for investigation of the distribution of nonelectrolytes of N-alcohol series between human red blood cells and extracellular medium. Membr Cell Biol 13(5):633-44. 2000. Code: 8

Safety of electronic cigarettes

UK

Disassembled parts of a first generation e-cigarette. A. LED light cover B. battery (also houses circuitry) C. atomizer (heating element) D. cartridge (mouthpiece) Parts of a second generation e-cigarette. An electronic cigarette is a battery-powered vaporizer.[1] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] An atomizer comprises a small heating element that vaporizes e-liquid and wicking material that draws liquid onto the coil.[3] When the user pushes a button,[4] or (in some variations) activates a pressure sensor by inhaling, the heating element then atomizes the liquid solution[5] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] The user inhales the aerosol, commonly called vapor, rather than cigarette smoke.[7] The aerosol provides a flavor and feel similar to tobacco smoking.[1] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] As the e-cigarette industry continues to evolve, new products are quickly developed and brought to market.[9] First generation e-cigarettes tend to look like tobacco cigarettes and so are called "cigalikes".[10] Most cigalikes look like cigarettes but there is some variation in size.[11] Second generation devices are larger overall and look less like tobacco cigarettes.[12] Third generation devices include mechanical mods and variable voltage devices.[10] The fourth generation includes Sub ohm tanks and temperature control devices.[13] The power source is the biggest component of an e-cigarette,[14] which is frequently a rechargeable lithium-ion battery.[15] A later-generation box mod e-cigarette. Image courtesy of Ecigclick An e-cigarette is a handheld battery-powered vaporizer that simulates smoking, but without tobacco combustion.[1] Once the user inhales, the airflow activates the pressure sensor, and then the heating element atomizes the liquid solution.[5] Most devices have a manual push-button switch to turn them on or off.[16] E-cigarettes do not turn on by trying to "light" the device with a flame.[4] The e-liquid reaches a temperature of roughly 100-250 °C within a chamber to create an aerosolized vapor.[6] However, variable voltage devices can raise the temperature.[17] A glycerin-only liquid vaporizes at a higher temperature than a propylene glycol-glycerin liquid.[17] Rather than cigarette smoke, the user inhales an aerosol, commonly but inaccurately called vapor.[7] E-cigarettes do not create vapor between puffs.[18] Vaping is different than tobacco smoking, but there are some similarities with their behavioral habits, including the hand-to-mouth action and a vapor that looks like cigarette smoke.[1] E-cigarettes provide a flavor and feel similar to smoking.[1] A noticeable difference between the traditional cigarette and the e-cigarette is sense of touch.[1] A traditional cigarette is smooth and light but an e-cigarette is rigid, cold and slightly heavier.[1] Since e-cigarettes are more complex than traditional cigarettes, a learning curve is needed to use them correctly.[19] Compared to traditional cigarettes, the general e-cigarette puff time is much longer, and requires a more forceful suction than a regular cigarette.[20] The volume of vapor created by e-cigarette devices in 2012 declined with vaping.[1] Thus, to create the same volume of vapor increasing puff force is needed.[1] Later-generation e-cigarettes with concentrated nicotine liquids may deliver nicotine at levels similar to traditional cigarettes.[21] Many e-cigarette versions include a voltage potentiometer to adjust the volume of vapor created.[4] The amount of vapor produced is controlled by the power from the battery, which has led some users to adjust their devices to increase battery power.[6] An ordinary cigarette compared to a "cigalike" e-cigarette E-cigarettes are usually approximately cylindrical, with many variations: pen-styles, tank-styles etc.[22] Some e-cigarettes look like traditional cigarettes, but others do not.[19] There are three main types of e-cigarettes: cigalikes, looking like cigarettes; eGos, bigger than cigalikes with refillable liquid tanks; and mods, assembled from basic parts or by altering existing products.[8] The primary parts that make up an e-cigarette are a mouthpiece, a cartridge (tank), a heating element/atomizer, a microprocessor, a battery, and possibly a LED light on the end.[2] The only exception to this are mechanical e-cigarettes (mods) which contain no electronics and the circuit is closed by using a mechanical action switch.[23] E-cigarettes are sold in disposable or reusable variants.[8] Disposable e-cigarettes are discarded once the liquid in the cartridge is used up, while rechargeable e-cigarettes may be used indefinitely.[24] A disposable e-cigarette lasts to around 400 puffs.[25] Reusable e-cigarettes are refilled by hand or exchanged for pre-filled cartridges, and ge